Entering the Lenten wilderness to receive the testimony of John against us is very difficult but necessary for repentance. The only way out of the wilderness is through it. The only way to receive John's offer of forgiveness and to receive also his charge against me, that I am an offspring of vipers.
If I'm accused, I immediately seek to defend myself. I am good at arguing my case (there is only person I ever really get into arguments with and I think she would agree with this). Perhaps I'm too good; already on the defense, I don't listen as much as prepare my next move. John is quicker than me. He first accuses me of my sinfulness and then, before I can say it, he anticipates my best defense, the "it's not what I've done but who I know" argument.
He says "Bear fruits that befit repentance, and do not begin to say to yourselves, `We have Abraham as our father'; for I tell you, God is able from these stones to raise up children to Abraham."
Partly, what John does here is prevent me from claiming my Christianity, my 'being saved,' as an excuse. Who I know should change how I live.
But knowing God is not about me, it's about God. As John puts it bluntly, God doesn't need me. (This seems perhaps harsh to say, However, I think it is true. It's what C S Lewis recognized, as he was coming to faith, when he said that it was better for heaven to exist then for him to get there.)
Though God does not need me, he wants me. But for him to have me, I must have him. To have him, I must accept that I don't need me either. I need God. Learning to leave me for him is repentance and repentance bears fruit.