I confess I always did find the imagery in Romans 6 to be a fairly strong, if not conclusive, argument for a prescriptive mode of baptism. But reading John Murray's Christian Baptism, published in 1952 in the Westminster Theological Journal and available from WTS here, I found his analysis helpful and not something I commonly find in literature on the topic.

Romans 6:3-4 ³ Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? ⁴ We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.

The two passages upon which the greater part of this phase of the argument for immersion rests are Romans 6:2-6; Colossians 2:11, 12. In essence the argument is that, since baptism represents union with Christ in his death and resurrection, immersion in water and emergence from it provide an analogy which graphically portrays that which is represented and sealed by baptism. Romans 6:3, 4 would appear to indicate such symbolism: "Or are ye ignorant that as many as were baptised into Christ Jesus were baptised into his death? Therefore we have been buried with him by baptism into death, in order that as Christ was raised from the dead through the glory of the Father, even so we should walk in newness of life.'' But more careful analysis will show that there is no necessary allusion to the mode of baptism.

It is beyond dispute that the leading thought of the apostle here is that of union with Christ in his death, burial, and resurrection. And verses 5 and 6 are confirmatory. They carry on the same thought in different terms: "For if we have become planted together in the likeness of his death, we shall be also in that of the resurrection: knowing this that our old man has been crucified with him, in order that the body of sin might be destroyed, to the end that we should no longer serve sin."

Paul is here dealing with the antinomian argument and, in order to rebut it, he sets forth the particular phases of union with Christ that are peculiarly adapted to that purpose, namely, union with Christ in his death, burial, and resurrection. He does this to show that every one who is united to Christ is, by virtue of the efficacy of Christ's death and the power of his resurrection, freed from the dominion of sin, lives a new resurrection life, and therefore cannot make his Christian faith and profession a plea for, or an inducement to, continuance in sin. Baptism, by which the Christian profession is registered and sealed, means baptism into union with Christ, and Paul is here stressing what such union means, particularly in reference to the death and resurrection of Christ. Believers died with Christ, they were planted together in the likeness of his death, they were buried with him, they were crucified with him, they were raised up with him and planted together in the likeness of his resurrection.

It is very easy to focus attention upon one or two of the terms which Paul here uses and make it appear that the indispensable mode of baptism is after the analogy of what we have arbitrarily selected. It is very easy to point to the expression "buried with him" in verse 4 and insist that only immersion provides any analogy to burial. But such procedure fails to take account of all that Paul says here. It should be noted that Paul not only says "buried together" (συνετάφημεν) but also "planted together" (σύμφυτοι) and "crucified together" (συνεσταυρώθη). These latter expressions indicate the union with Christ which is symbolised and sealed by baptism just as surely as does "buried together". But it is only too apparent that they do not bear any analogy to immersion. Even if it should be conceded that the different shades of meaning possible in the case of "planted together'' (σύμφυτοι) leave room for some resemblance to immersion, yet no resemblance can obtain in the case of "crucified together". We are represented as having been hung on the cross together with Christ, and that phase of union with Christ is represented by our baptism into Christ not one whit less than our death in him and our burial with him, not one whit less than our being planted with him in the likeness of his death and our being raised with him in the power of his resurrection. When all of Paul's expressions are taken into account we see that burial with Christ can be appealed to as providing an index to the mode of baptism no more than can crucifixion with him. And since the latter does not indicate the mode of baptism there is no validity to the argument that burial does. The fact is that there are many aspects to our union with Christ. It is arbitrary to select one aspect and find in the language used to set it forth the essence of the mode of baptism. Such procedure is indefensible unless it can be carried through consistently. It cannot be carried through consistently here and therefore it is arbitrary and invalid. This passage as a whole points up the arbitrariness of such procedure by emphasising a phase of our union with Christ that bears no analogy whatsoever to that of immersion.

Confirmatory of this conclusion is Galatians 3:27. Here another implication of our union with Christ is argued by the apostle. The form of statement is closely similar to that of Romans 6:3. In Romans 6:3 Paul says: "As many as were baptised into Christ were baptised into his death", and in Galatians 3:27: "For as many as were baptised into Christ did put on Christ". It would be just as legitimate to insist that there is reference to the mode of baptism in Galatians 3:27 as in Romans 6:3. But in Galatians 3:27 the figure used by the apostle to set forth the import of baptism into Christ has no resemblance to immersion. It is the figure of putting on a garment. The plain inference is that Paul is not alluding to the mode of baptism at all. And neither may we suppose that he is in Romans 6:2-6. We should be faced with contradictory testimony as to the mode of baptism if we supposed that these passages allude to it.

In I Corinthians 12:13 we have the same effect. "For by one Spirit have we all been baptised into one body." The figure here is the making up of one unified organism and is quite foreign to the notion of immersion.

The only sane conclusion is that in none of these cases is reference made to the mode of baptism. The emphasis is plainly upon the meaning of baptism into Christ, that is to say, of union with him. Indeed, so paramount is the thought of union with Christ that the allusion to the rite of baptism need not be considered as overt. While it might not be proper to say that allusion to the rite of baptism is not at all present in the use of the word "baptise" in these passages, yet in such expressions as "baptised into Christ", "baptised into his death" (Rom. 6:3; Gal. 3:27), and "baptised into one body" (I Cor. 12:13), it is not the rite of baptism that is in the foreground but rather the idea of union with Christ. "Being baptised into" is a way of expressing "union with". To be "baptised into Moses" (I Cor. 10:2) is to be bound to Moses in the fellowship of that covenant of which Moses was the mediator. In a word, it is to be a disciple of Moses. Paul protests to the Corinthians that they were not baptised "into the name of Paul" (I Cor. 1:13): it would have meant that they had been baptised into the discipleship of Paul rather than into that of Jesus. To be ''baptised into Christ'' is to be bound to him in the bonds of that union that makes us the beneficiaries of all the blessings of redemption and pledges us to his Lordship. The rite of baptism is the sign and seal of this union. But the langauge of the symbol and seal becomes so closely attached to that which the symbol represents that this language may be used to express that truth when the symbol itself has receded into the background of thought. Hence in these passages which have been considered it is not the rite of baptism that is in the foreground. Indeed, reference to the rite may have receded almost to the point of disappearance. It is union with Christ that claims the thought, and the language of baptism has been appropriated to give emphasis to that thought as well as to express the fulness and richness of the union involved.