1. Educate himself so he can truly dialogue on such matters;
2. Stand down on religious matters - he is embarrassing himself and the rest of us.
I'm hoping he takes the first option.
The most embarrassing thing about the segment was at the end, O'Reilly tried to make it seem like Bill was completely wrong about killing your neighbors for desecrating Sundays when he did not know anymore but less than what Maher knew about it. To make it worse, he even gave the wrong answer to the objection!!! A complete facepalm.
Debunking Christianity: Bill O'Reilly vs. Bill Maher On Religion - 09/30/10