Bring forth therefore fruits worthy of repentance. In other words, "Since you profess to have taken flight from the wrath to come, show at once, by your change of life, that your repentance is worth something, has some meaning in it."
Begin not to say within yourselves, We have Abraham to our father. These words show that John had the splendid courage to strike boldly at the very root of Jewish pride. Gradually Jewish belief in the especial favor of God, which they were to enjoy through all eternity, had grown up till it resulted in such extravagant expressions as these: "Abraham would sit at the gates of hell, and would not permit any circumcised Israelite of decent moral character to enter it;" "A single Israelite is worth more in God's sight than all the nations of the world;" "The world was made for their (Israel's) sake."
This incredible arrogancy grew as their earthly fortunes became darker and darker. Only an eternity of bliss, of which they alone were to be partakers, could make up for the woes they were made to suffer here, while an eternity of anguish for the Gentile world outside Israel was a necessary vengeance for the indignities this Gentile world had inflicted upon the chosen people.
Long ago the great Hebrew prophets had warned the deluded race that their election would profit them nothing if they failed in their duties to their God and their neighbor. For I say unto you, That God is able of these stones to raise up children unto Abraham; pointing, no doubt, to the rough shingle lying on the river Jordan's banks.
John's thought was the same which Paul afterwards expressed to the Galatians in his own nervous language, "Know ye therefore that they which are of faith, the same are the children of Abraham;" "And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise" (Galatians 3:7, Galatians 3:29).