Like an Old Testament prophet (cf. Amos 3:2), John tore to tatters any plea that could be offered that his listeners were God’s chosen people, the children of Abraham. Does God want children of Abraham?—John pointed to the stones on the ground, and said, if God wanted, he could make children of Abraham out of them; a word and he could have as many children of Abraham as he wished. It was something else that God sought.
“John,” writes the historian Josephus a generation later, “was a good man, and commanded the Jews to exercise virtue both in justice toward one another and piety towards God, and so to come to baptism; for so baptism would be acceptable to God if they made use of it, not to excuse certain sins, but for the purification of the body, provided that the soul was thoroughly purified beforehand by righteousness."[28] This interpretation of John’s baptism makes it look very like the baptisms and other purificatory rites of the heathen. The Gospels attribute to John a message, richer and more powerful, but essentially the same; and the criticism of Jesus confirms the account. The great note in his preaching is judgement; the Kingdom of God is coming, and it begins with judgement. Again, it is like Amos—“The axe is at the root of the tree,” “His fan is in His hand.” And as men listened to the man and looked at him—his intense belief in his message, backed up by a stern self-discipline, a whole life inspired, infused by conviction—they believed this message of the axe, the fan, and the fire. They asked and as we have seen received his guidance on the conduct of life; they accepted his baptism, and set about the amending of character (Matt. 21:32).
Jesus makes it quite clear that he held John to be an entirely exceptional man, and that he had no doubt that John’s teaching was from God (Matt. 21:32; Luke 7:35, 20:4; and, of course, Luke 7:26-28). It was all in the line of the great prophets; and the Fourth Gospel shows it us once more in the work of the Holy Spirit—“when he is come, he will reprove (convict) the world of sin, and of righteousness, and of judgement” (John 16:8). And yet, as Jesus says, there is all the difference in the world between his own Gospel and the teaching of the Baptist.