What “good news” is there when someone calls you “a brood of vipers”?  Dr. Luke helps his readers see that while there is a call for repentance and of coming judgement, that the good new, the “Gospel” is that John the Baptizer as well as Jesus tell us that that there is still time to repent and turn. God is gracious and calls to all humanity to turn from sin and live lives bearing fruit of that repentance.