John the Baptist has his first schizophrenic episode, which causes him to run off into the wilderness like, oh, I don't know The Unibomber and shriek at people that they are a generation of vipers (v. 7) and to repent and cut down non-fruit-bearing trees and burn them. As Monty Python teaches us, with prophets the crazier the better, so naturally he has a rapt audience. They ask how they can get into heaven. Well, first of all you have to donate most of your worldly goods to the poor, so Mitt Romney, donating 7 million smacks of his 43 million dollarincome isn't quite going to cut it. But he will be fine in Mormon heaven. Other things you can do to get into heaven: have a fair tax code, don't kill people, don't lie, be happy with your wages. So, heaven will be pretty empty, then, I guess.
All this makes people start to wonder if John-boy isn't the Messiah. He says no, he's just here to baptise people with water, but someone even better than him is on his way to baptise them with fire. See what I mean about the crazier the better?
Herod hears about John, and also that he insulted his sister-in-law, so he locks him up in prison. But before that, Jesus came along to get baptised and god was pleased, because heaven forbid the narrative should be linear. In the time it has taken us to flip from chapter 2 to chapter 3, Jesus has aged another 18 years and is now 30.
The last 15 verses of this chapter are Jesus' genealogy, which I am not going to read on principle.