I gotta have my orange juice.

I indeed baptize you with water unto repentance, but He who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and fire. (Matthew 3:11 NKJV)

First of all, I am not a language scholar and I hesitate to make much of a preposition.

Second, John’s baptism is not the same thing as Trinitarian baptism, so we should hesitate to make straight-line applications from John to Jesus and his church. In a manner of speaking, John was bringing faithful covenant people back to life after their having come into contact with death. By contrast, Jesus by baptism brings people into his covenant for the first time, bringing them to life once and for all.

Nevertheless, the idea of a baptism being unto or toward repentance is significant. Rather than baptism being, as Robert Stein would have it, a mere synecdoche for a faith-repentance-baptism sequence, this shows that baptism is in fact a performance of repentance. Just as James teaches us that faith must be performed in order to be fully realized, so too repentance must be performed in order to be fully realized.

This by itself is not proof of paedobaptism, though it is highly consistent with paedobaptism and paedofaith. But it is proof against a facile credobaptism: if you require someone to repent before their baptism, you are in a sense requiring the impossible.