According to Kim Pallister, Microsoft's casual game guy, Bible Fight is "the most sacrilegious game ever."
It is a straightforward Streetfighter-style game, in which you and your opponent (either controlled by the computer or by someone else whanging on the other side of the keyboard) punch and kick each other until one or the other achieves victory.
As with other games of this style, there are a variety of characters, each of whom has his own combo moves that do extra damage, if you can hit the right key combination quickly enough.
Except that--the characters are Mary, Eve, Jesus, Moses, Noah, and Satan. And the special moves are things like Mary's Halo Toss, and Jesus's Loaves and Fishes.