I read this book a few years back. It's a sci-fi/fantasy with humor novel. The story is about two babies accidentally switched at birth. One of the babies happens to be the anti-christ. Because of the switch, he's raised as an average human. When as an adult he finds out who he is, he doesn't want the job of being the anti-christ. Meanwhile while he was growing up, there are two goofy demons desperately trying to find him.

Any ideas what the title is of this book??

Man I loved this book it was Good Omens by Terry Pratchett and Neil Gaiman.

Yep, that's Good Omens one of the best books either author has written.