I would classify myself as a Christian, and I've read the books. I don't like most Christian-targetted media because it's... how to put this lightly... terrible. The books weren't all that great, either, but they were easy to read and entertaining. Completely ridiculous, but entertaining.
But the game... I have to ask. Isn't the whole point of the book series (and the books of Revelation, Daniel, etc. for that matter) that the actual people in the battle don't have a whole lot to do with the outcome? If you lose in the game, does that mean that Satan beat God? You're kind of crapping on your own concept, Left Behind Games. Way to go.