The “rollcall of the faithful” in Hebrews 11 lists many heroes of the OT and declares them saved by faith – even though they lived under either the Abrahamic or Mosaic covenants – because the promises God made to Abraham never went away.
(Heb 11:13-16 ESV) These all died in faith, not having received the things promised, but having seen them and greeted them from afar, and having acknowledged that they were strangers and exiles on the earth. 14 For people who speak thus make it clear that they are seeking a homeland. 15 If they had been thinking of that land from which they had gone out, they would have had opportunity to return. 16 But as it is, they desire a better country, that is, a heavenly one. Therefore God is not ashamed to be called their God, for he has prepared for them a city.
This chapter would make no sense at all unless (a) Israel found salvation through faith, rather than works, and (b) we Christians are saved by the same faith. Again, of course, before Jesus, the Jews believed in a Messiah promised but not yet revealed; Christians believe in the revealed Messiah.
So this brings us back to baptism. The key faith versus works passages speak of the sufficiency of faith in Jesus to save. They never say that circumcision was once essential and now baptism replaces circumcision as the essential initiatory rite. Rather, they say that faith was sufficient for Abraham and for Israel, and therefore faith is sufficient for Gentiles. Hence, there is no need for something that is other than faith, such as circumcision.
Baptism is mentioned and accorded a vital place, but it doesn’t receive nearly the same emphasis or centrality as faith. Only faith goes back to Abraham. Only faith allowed God to save Israel despite their inability to keep the Law of Moses. And only faith allows God to save Gentiles without circumcision. All of Paul’s arguments are centered and focused on faith in Jesus and the receipt of the Spirit (which I’ve not tried to summarize here). Baptism is mentioned and never belittled. But baptism is never at the center of Paul’s arguments.
In Romans, Paul doesn’t even mention baptism in his discussion of how Christians are saved in Rom 1 – 5. It doesn’t come up until Paul deals with the ethical implications of salvation by faith: “Shall we go on sinning that grace may abound?” (Rom 6:1). But it’s assumed to be universal, well understood, and very closely tied to our forgiveness.
In Galatians, Paul covers nearly three chapters on our salvation and the gospel and only mentions baptism in Gal 3:27 as explaining or demonstrating the unity that we all have by faith in Jesus.
In Ephesians, Paul covers salvation by faith for three chapters, and then early in chapter 4 mentions “one baptism” as one of the seven ones that demonstrate the unity of Jews and Gentiles through Jesus.
In Hebrews, which speaks to the superiority of Jesus and Christianity to Judaism, baptism is only mentioned in passing (Heb 10:22 and possibly 6:2) –
(Heb 10:19-23 ESV) Therefore, brothers, since we have confidence to enter the holy places by the blood of Jesus, 20 by the new and living way that he opened for us through the curtain, that is, through his flesh, 21 and since we have a great priest over the house of God, 22 let us draw near with a true heart in full assurance of faith, with our hearts sprinkled clean from an evil conscience and our bodies washed with pure water. 23 Let us hold fast the confession of our hope without wavering, for he who promised is faithful.
Baptism is metaphorically compared to the washing Jews had to undergo to enter the Temple, where the Jews approached God’s presence in the Holy of Holies. Our confidence is in the sacrifice of Jesus (v. 19), but baptism helps assure us that our faith allows us to draw near to God thanks to the work of Jesus.
So it’s not possible that our salvation is based on baptism. Over and over, Paul points us to faith in Jesus. Baptism is not the linchpin. It’s not the foundation. It’s, rather, a critically important assurance of our salvation – a form of assurance that was universally practiced by the early church and administered to all converts who confessed Jesus. In fact, I believe it’s even more than that. But it’s not co-equal with faith in Paul’s theology.