Luke 3:3

They show that things were completely out of course. Government was in the hands of the Gentiles. Even in Israel things were in confusion, for there were two high priests instead of one. So repentance was the dominant note in his preaching. Earlier prophets had reasoned with Israel and called them back to the broken law. John no longer does this, but demands repentance.

Nothing would interfere with the purposes of grace. Not changes in the world. Not the lowering of the Lord's people. Not the strange pairing of priests. Not the carving up of the land by foreigners. On the contrary, grace loves to take up men and things at their worst, and shows what God is towards the needy.

Repentance was what characterised John's preaching. That does not mean repentance was ever less than binding; it always binds every sinful soul that comes to the knowledge of God. Christianity does not lessen repentance; it deepens it. Yet you could not call repentance characteristic of Christianity — faith is much more so... In John the Baptist's preaching it was the emphatic word that described the character of his message.

The way of the Lord is prepared only by bringing the mountains down and filling up the valleys. That brings all flesh to a common level before God, so that all may see the salvation of God. So the baptism is to Jordan, the river of death. Men's sins bring them there, not their goodness — but there they find forgiveness.

Still, it was for forgiveness — "a baptism of repentance for the forgiveness of sins." That forgiveness was not present yet, so the baptism could not be a testimony of sins already forgiven. It looked ahead to the One coming, whose forerunner John was.

His business was to take the nation up on the ground where it stood and call it to repentance. In fact he formed a remnant to receive Christ. Forgiveness of sins was in view for those he baptised... When Peter preaches, he preaches Jesus rejected and exalted, made Lord and Christ... the baptism was to the forgiveness of sins, because the work that gives it fully was now done.

Through John's baptism the godly remnant took separate ground from the nation as a whole, waiting for the Messiah to come. They judged themselves, and cleared themselves of the sinful condition of the nation. John baptised the Lord too, and so He took His place among the repentant in Israel — not confessing sins, but fulfilling righteousness.

Scripture is just as plain that John's baptism is quite distinct from Christian baptism. Some disciples had already received John's baptism, yet they had to be baptised to Christ when they received the full truth of the gospel (Acts 19)... Confessing a coming Messiah is a far cry from confessing His death and resurrection. That difference is the root of differences that carry weighty consequences.