One of the strongest texts supporting the
salvific efficacy of water baptism is Rom 6:3-4 (see my exegesis here).
Commentators of all theological persuasions, including those who hold to a
strictly symbolic view of baptism, are forced by the proper rules of exegesis,
that the apostle Paul is discussing water baptism, notwithstanding the protestations
of some who desperately distort the meaning of the term βαπτιιζω to
support their traditions (see this post responding to John Greer, current moderator of the Free Presbyterian Church of Ulster on this very issue).
I recently encountered this passage from a
Reformed author who, personally, based on his denomination’s teachings, rejects
baptismal regeneration, but has the intellectual integrity and honesty to admit that (1)
water baptism is being discussed in Rom 6 and (2) it is the instrumental meanings
through which one is “united” with Christ and participates in the death and
(new) life of Christ. Commenting on Rom 6:5 ("For if we have been united
with him in a death like his, we will certainly be united with him in a
resurrection like his" [NRSV]), he writes:
The explanatory γαρ in 6:5 links the verse with his previous comments about the believer’s death with Christ through water-baptism in 6:3-4. His argument appears to be that believers died to sin and should no longer live under its power (6:2). Their water-baptism proves that they participate in the death of Jesus and experience a spiritual death to the power of sin (6:3). Therefore, Paul concludes that believers have been buried with Jesus through their participation in water-baptism, a baptism that identifies them with the death of Jesus (their representative [5:12-21]) and thereby kills the power of sin in their lives, so that they would live with Jesus in the resurrection just as Jesus presently lives in the power of his physical resurrection (6:4). Believers who died to the power of sin by being baptized into Jesus’ death will certainly (αλλα και) participate in a physical resurrection just as Jesus died and resurrected, because those who died to the power of sin (just as Jesus died = τω ομοιωματι του θανατου αυτου) will participate in a future resurrection (just as Jesus has already been resurrected) (6:5). (Jarvis J. Williams, Christ Died for Our Sins: Representation and Substitution in Romans and their Jewish Martyrological Background [Eugene, Oreg.: Pickwick Publications, 2015], 178).