The Gospel That Would Go Throughout The World

Tertullian acknowledged that people were justified apart from baptism during Jesus' public ministry. But in response to critics of baptismal regeneration, he wrote, "in days gone by, there was salvation by means of bare faith, before the passion and resurrection of the Lord", whereas now "the law of baptizing has been imposed" (On Baptism 13).

I've noted before that John's gospel emphasizes Jesus' statements about salvation during his public ministry (John 3:16, 5:24, 11:25-26, etc.), and John tells us that he wrote his gospel to lead people to salvation (John 20:31), using language similar to Jesus' language earlier in the gospel. If the means of being justified had changed in the manner Tertullian suggests after the resurrection, then John's emphasis on Jesus' pre-resurrection teachings about justification makes less sense. And John's repetition of Jesus' language in 20:31, without adding any reference to baptism, makes less sense.

Similarly, Paul, Clement of Rome, and other early Christians made an appeal to the continuity between how people were justified during the Old Testament era and how they're justified after Jesus' coming. There's often an appeal to Abraham, sometimes to Genesis 15:6 in particular. That goes back to Jesus himself (Luke 19:9). There was one means by which God had been justifying people "from the beginning" (Clement of Rome, First Clement 32).

Beyond these lines of evidence for continuity rather than discontinuity between how people were justified during and after Jesus' public ministry, we should ask which view makes more sense from a more abstract perspective. Would Jesus make justification apart from baptism such a prominent part of his ministry (as conceded by Tertullian and other advocates of baptismal regeneration), participate in multiple types of non-justifying baptism (the baptisms of John and Jesus in John 3:22-4:2), and refer to how this gospel will go throughout the world in later history (Matthew 24:14, 26:13), even though he was expecting a change to baptismal regeneration shortly afterward? Even before Jesus made those comments, Isaiah anticipated the bringing of "good news" (the gospel) and an "everlasting covenant" (Isaiah 61:1, 61:8) in a passage that's eschatological. Jesus referred to how his bringing of the gospel was the beginning of the fulfillment of the passage (Luke 4:16-21). The Isaiah 61 passage and Jesus' comments on it make the most sense if how people are justified, which is a major aspect of the gospel (as reflected in Acts 15, Romans, Galatians, etc.), is consistent rather than inconsistent over time.

The issue here isn't whether it's possible that Jesus and the other relevant sources only had some kind of lesser rather than greater degree of continuity in mind when they referred to continuity between how justification is received after Jesus' public ministry and how it was received earlier. Rather, the issue is which view makes more sense of the evidence. The relevant sources put a lot of emphasis on continuity in how people have been justified (e.g., by mentioning it multiple times, in multiple ways, in multiple contexts), specifically mention the means by which we receive justification (faith) as unchanging throughout history, and say that the means of receiving justification is a foundational issue. Under those circumstances, justification occurring through faith throughout history makes more sense than a change taking place at the time when John 3:5 was spoken, after the crucifixion, after Jesus' resurrection, at the time of the Great Commission, or whenever else (depending on which advocate of baptismal regeneration you talk to).