Romans 6:3-4, what does it mean to be baptized into Christ Jesus?  It means our water baptism is a time when we are baptized into the death of Jesus Christ.

For a more detailed explanation read the following from the College Press NIV Commentary:

6:3 Or don’t you know what happened to you in your baptism? Literally Paul says “or are you ignorant” of this. He asks this sort of question quite often. It has the tone of a mild rebuke, implying that you should know this, but just in case you do not I will explain it. In this instance his question has to do with baptism. Without a doubt all of Paul’s Christian readers would have remembered the time and event of their immersion, since this was a part of the basic presentation of the gospel and of becoming a Christian. However, they may not have understood the deeper spiritual significance of this act; this is what Paul now explains.

Don’t you know that all of us who were baptized into Christ Jesus were baptized into his death? “All of us who were baptized” means all Christians; in the NT there is no such thing as an unbaptized Christian. “Baptized” refers to water baptism and everything the NT includes in it. It is fairly common for expositors to claim that the baptism to which Paul refers in Romans 6 is a “spiritual” or “dry” baptism only, as distinct from water baptism. For example, Lloyd-Jones concludes “that baptism by water is not in the mind of the Apostle at all in these two verses [6:3-4]; instead it is the baptism that is wrought by the Spirit” (36). Those who hold to such a view are almost always from Protestant traditions that have adopted Zwingli’s innovative separation of baptism from the time of salvation. Stott’s view is surely the more reasonable, namely, that in the NT “baptism means water baptism unless in the context it is stated to the contrary” (173).

On the other hand, even though Moo agrees that water baptism is in view (I:376), he wrongly concludes that baptism here “functions as shorthand for the conversion experience as a whole” (I:371). Certainly what Paul has already written (and the NT writings as a whole) make it obvious that faith and repentance are presupposed here as precursors of baptism. But what happens in the initial moment of faith and repentance, and in the conversion experience as a whole, are not Paul’s point here. He specifically refers to what happens in baptism.

The Apostle refers to baptism as being “baptism into Christ Jesus.” That he does not dwell on this point shows that it was a basic truth that any Christian would already know. To be baptized into Christ means to be baptized for the purpose of entering into a specific relationship with him, or into a living union with him. As Moo says (I:377), the preposition “into” (eis) has the connotation of movement from one space to another, as well as the connotation of purpose. Thus as Moo puts it, “baptized into Christ” means “baptized with a view to being united with Christ.” See Gal 3:27.

This union with Christ is not effected by the ritual itself, either by the water or by the act. It is accomplished by the grace and power of the living God alone. That it happens in the act of baptism is simply a matter of God’s free and sovereign choice; he has appropriately designated this event as the occasion for the beginning of this saving union with the Redeemer. It is not wrong to say that the external ritual of water baptism symbolizes or has a metaphorical connection with this saving union. What is wrong is to separate the symbol from the reality as if the temporal connection between them is irrelevant.

All of the above is part of what Paul assumes his Christian audience already knows. In the latter part of the verse he begins to talk about the point of which they may be ignorant, the point that he wants to stress in reply to the question in v. 1. Don’t you know, he asks, that you were baptized into the death of Christ? If you were baptized “into Christ” as such, don’t you realize that this means you were baptized into a union with Christ in his death? Ordinarily when we think about coming into contact with the death of Christ and its benefits, we think of the atoning and justifying power of his blood, and we think of the fact that baptism is for the forgiveness of sins (Acts 2:38), or justification. But here Paul primarily has something else in mind. He is letting us know that our union with Christ’s death in our baptism had a result that is crucial for our victory over sin itself. This result is explained in the next verse.

6:4 We were therefore buried with him through baptism into death…. Here Paul continues to make his point by drawing a conclusion from his preceding statement, as indicated by “therefore.” The main point of this conclusion is the phrase “into death.” First of all, whose death does Paul mean? He has already said we are baptized into Christ’s death (6:3). The phrase “buried with him” basically repeats this. Therefore we must conclude that “into death” means something else, namely, our own death to sin. When we were baptized into Christ’s death (or buried with him through baptism), we were actually baptized/buried into our own death as well. According to v. 2, “we died to sin.” This is the main point of this whole section and the main reason why grace does not imply antinomianism. The rest of this section (vv. 3-14) is meant to explain this death to sin. The introduction of the subject of baptism (“or don’t you know”) leads us to expect some specific reference to this death in connection with baptism. But if the phrase “into death” here in v. 4 does not refer to our personal death to sin, then this passage does not connect it with baptism at all, and there would seem to be no good reason even to bring up the subject of baptism. Also, everything in the following context presupposes such a reference to our own death to sin. Therefore I vigorously disagree with those who see “into death” as referring to Christ’s death only. It may include that, but the main reference is to our own personal death to sin.

The implication is that in some true and significant sense, the death of Jesus has a death-dealing power in reference to sin. When we became united with Christ’s death in baptism, our old sinful self was put to death—not by our own will power, but by the power of his holy cross. It is as if, in his death, Jesus became a flame that is capable of extinguishing everything having to do with sin and death. When we are baptized into his death (buried with him in baptism), we touch this flame; and it consumes the “old man” of sin, and sets us ablaze with a holy fire that continues to purge the residual sin from our lives.

I take the phrase “into death” as modifying the verb, “we were buried,” though many take it as modifying “baptism.” Some have trouble with the former view because “the idea of burial into death seems a forced one” (Käsemann, 166; see Cranfield, I:304). However, Dunn agrees that the phrase goes with the verb, and argues that the ancients would have seen nothing strange about “burial unto death” (I:314). Indeed, burial is one of the most effective methods of putting someone to death.

Why does Paul say that “we were buried with him”? Obviously in the experience of most people, including Christ, death precedes burial and is distinct from it. Burial is simply the natural sequel to death. It is assumed that this same distinction and sequence apply to the sinner’s death to sin and his burial with Christ. It is assumed that the actual death to sin occurs prior to baptism, usually when faith and/or repentance begins. This is followed by baptism as a ritual burial of the corpse. The baptismal burial “sets the seal on death” (Bruce, 139) or establishes its finality (Moo, I:382) and certifies its reality (Mounce, 149).

I see an entirely different picture here, however. Paul says nothing about dying first, and then being buried in baptism. Rather, he says very clearly and pointedly that were were buried with him through baptism, into death. The death and the burial are not separated by time. The only sequential relationship here is that the burial precedes the death as cause precedes effect. Also, both the death and the burial occur through baptism. There is no significant difference between the burial and the death. To be “buried with him through baptism” is just another way of saying “baptized into his death.”

Then why does Paul adjust the image in v. 4a and speak of burial at all, rather than just death as such? For two reasons. First, his main point is that by being baptized into Christ’s death, we have been baptized into our own death; and it would be awkward and ambiguous to repeat “baptized into his death” in v. 4. By switching to the image of burial he can make this point in a much more smooth and unambiguous way. Second, the image of burial is naturally suggested by the reference to baptism, which as an act of immersion into water is a perfect physical symbol of the deaths and resurrections (Christ’s and ours) that are represented and occurring there. It is tragic that so many would rob baptism of this, its most central symbolism. I agree with all those who understand that baptism is immersion, and who declare that only in this form can its connection with the realities of death, burial, and resurrection—both Christ’s and ours—have any meaning at all.

It is necessary at this point to raise the question as to exactly when the sinner’s death to sin occurs. Paul says very clearly that we were “buried with him through baptism into (our) death.” However, it seems that most interpreters are determined to locate it at some other point in time, anywhere but in baptism itself. Cranfield’s view is typical. He denies that baptism “actually relates the person concerned to Christ’s death, since this relationship is already an objective reality before baptism takes place.” Baptism is just a pledge of “that death which the person concerned has already died” (I:303). Restoration writers often hold this view. Lard declares that “we… died to sin before our baptism” (195). Our death to sin was brought about “preceding our baptism,” says DeWelt (90).

If not in baptism, then when does our death to sin occur? There are two main views. Some say we died with Christ on his cross, and thus at a particular point in his history, not ours. We “died with him on the cross,” says Mounce (151). “When Christ died on the cross, his true followers all died there with him,” says Hendriksen (I:198). But if this is true, then there is no point of time in the sinner’s own history when this death to sin occurs. If it occurs on the cross itself, then it has been infallibly accomplished once for all for those who were in Christ at that time. The result is either universal salvation or limited atonement.

The second main non-baptismal view says that the sinner’s death to sin occurs at the moment of faith and/or repentance. This is a common Restoration view. Lard says, “We die to sin when we believe in Christ and repent of our sins”; baptism is just the burial of the dead man (195-196). DeWelt’s view is the same (90-91); see also Moser (65) and Lipscomb (114). Of course this view is common outside the Restoration Movement. Godet’s statement is typical, that “the death to sin” is “implicitly included in faith.” Baptism is a burial, and “people do not bury the living” (238-239). “When we believe we die to sin, and when we are baptized the burial is carried out,” declares Morris (248). Baptism just symbolizes what has already occurred.

At least this second view places our death to sin at a point within our own lifetime. The problem, though, is that Paul himself says nothing in this passage about either faith or repentance. If either or both of these are the time when death to sin occurs, why did he not just say that? Why didn’t he just say, “Don’t you know that all of us who believed and repented were united with Christ’s death when we believed and repented? Don’t you know that we believed and repented into death?” But he says nothing of the kind; he says it happens “through baptism.” Nor does he say anything about baptism being only a symbol of an already-existing reality.

Paul’s language is clear. He says we were baptized into Christ’s death, and that we were buried with him into death through baptism. The words “through baptism” belie all notions of post-reality symbolism. They connect our baptism and our death to sin together as cause and effect. This does not mean that the water or the physical act as such produces this spiritual effect. Only the spiritual working of God himself, which he graciously performs in conjunction with the physical act, can cause us to die to sin and rise again.

Paul says that we are baptized into Christ’s death, and that through baptism we are buried with him into our own death to sin. This means that God has so worked it that in some manner the death of Jesus Christ with all its saving benefits is literally present to the believing sinner and actually touches him in the act of baptism; and this union produces our death to sin. Käsemann well says, “Christ alone died on the cross.” Baptism is “our reception of his act and participation in his fate” (166). In baptism the event of the cross “lays hold of him who submits to this act and it does so in a documentary, visible, existence-changing fashion…. The cross is actualized in the act of baptism” (168).

Are we saying, then, that baptism is both the occasion and the means by which the believing sinner is regenerated? In reality, it is impossible to separate occasion and means. We can say that baptism is both if we remember one thing, namely, that the one act of baptism (Eph 4:5) is a dual event in which physical and spiritual acts are taking place simultaneously. While the believing sinner’s body is being immersed into water by a human agent, God himself is working the works of salvation upon the sinner’s spirit, including justification and regeneration. Physical immersion is the occasion, and the simultaneous working of God is the means of producing these effects. Thus in a general way we can say yes, baptism is a means of salvation in the sense that the total event includes not just the physical immersion but also the efficacious works of God.

In what sense, then, is faith itself (and perhaps repentance also) a means of salvation? Col 2:12 (NASB only) brings all these elements together: “Having been buried with Him in baptism, in which you were also raised up with Him through faith in the working of God, who raised Him from the dead.” “Buried with him” and “raised up with him” are saving acts that effect justification and regeneration. “In baptism” (physical immersion) indicates the time, place, or occasion when these saving acts take place. “The working of God” is the active means that brings about these saving acts, and “through faith” is the passive means by which we receive their results.

Without a doubt our death to sin is one of the most important events in our lives, and Paul here makes it the keystone of his reply to the first antinomian objection to grace (6:2). Yet in a real sense this death is not the main event but is itself a means to an even greater end: resurrection. This is seen in the rest of v. 4, which is introduced by the word ἵνα (hina), indicating purpose and translated in order that. We were buried with Christ through baptism into our death to sin so that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life. The death of our old man simply prepares the way for our new life.

The resurrection of Jesus is introduced here not just as an analogy of our own spiritual resurrection, but, like his death, as an essential part of his saving work with which we come into contact in baptism. The resurrection of Jesus Christ represents and generates infinite life-giving power (Eph 1:18-23; Heb 7:16), a power that produces in us the ability to walk in newness of life. “From the dead” is literally “from among the dead,” but the sense is “from the state of death.” That Jesus was raised “through the glory of the Father” probably means “through the Father’s gloriously displayed power.” (See under 1:21.) Glory and power are often closely related (Cranfield, I:304-305).

The main idea here is “in order that… we too may live a new life.” This is a very condensed statement. Paul does not specifically say that we were “raised from the dead” just as Christ was raised. It is definitely assumed, however, since he mentions it later (6:11, 13) and elsewhere (Eph 2:5-6; Col 2:12-13). The word “too” connects his resurrection and ours.

That this resurrection also occurs in baptism, as the counterpart to burial, is implied in this verse and specifically stated in Col 2:12 (NASB only). We emphatically reject, as the tragic legacy of Zwingli’s revisionist baptismal theology, such statements as this by Mounce (150): “We do not believe… that rebirth is in any real sense connected to water baptism.” As we will see below, there is a future aspect of our resurrection with Christ, but that must not be allowed to obscure the all-important spiritual resurrection that occurs in our baptism.

The ultimate purpose and goal of both our death to sin and our resurrection with Christ is the actual living of a new life. The NIV translation “may live a new life” is too sanitized. The Greek literally reads “might walk in newness of life” (NASB). The emphasis is on life. Prior to our conversion we were dead in our trespasses and sins (Eph 2:1, 5), and our whole existence was under the pall of death. But in baptism all this was changed. Now the power that controls us is life, not death. Our existence is characterized by life rather than death.

This is indeed a newness of life—a new kind of life that transcends even that innocent state of life in which we were born and in which we existed until we sinned (7:9). It is life derived from Christ’s own glorified existence, life transmitted to us by the Spirit of life (8:2), life that is in continuity with our ultimate eschatological and eternal life (6:23).

We do not just “live” this life; we walk in it. This word (περιπατέω, peripateō) is one of Paul’s favorite expressions for one’s behavior or daily conduct, good or bad. He uses it over 30 times in this sense, no doubt under the influence of a similar idiom in the OT (Dunn, I:315-316).

To “walk in newness of life” means to live a holy life, a life of obedience to God’s laws. This is the whole purpose of our death to sin and resurrection with Christ. Rather than the antinomian inference that grace encourages sinning, it does just the opposite. By design and in effect it separates us from sin and sets us on the road of righteousness. The verb “to walk” is subjunctive, hence the translation “might walk.” Death to sin and resurrection to life create the possibility and ability of walking in the new, holy life; but we must take the responsibility of applying this new life-power to our daily conduct. “Shall we remain in sin?” is the objection. Paul replies, “How could you? You have died to sin and been made alive in Jesus Christ! So walk in the possibilities and the power of your new life! Just do it!”
College Press NIV Commentary, The – The College Press NIV Commentary – Romans Volume 1.