The Torah
Hi, I am God. Do not believe in any of those other gods; it makes me very angry. I like Jews. If you are Jewish, I will toy with you for a few thousand years before I let you have that small speck of land. I'm doing this because you are my favorite people.
The Gospels
Hi, it's God again. There's been a change of plans. I don't like the way things have turned out. After all I've done for the Jews, they just don't seem to appreciate me. I'm sick and tired of making all these personal appearances. I'm going to send down my son (well, actually myself, as my son is myself and I am my son... never mind; I don't expect you to comprehend). Please do as he tells you.
The Koran
Okay, this is the last time I'm going to be writing, so pay attention. There are no other Gods. I am the only one. My first two books were okay, but this one is the one that counts. If you believe in me and pray like you're supposed to, then you have nothing to fear, for I am your protector. If you are an unbeliever, then beware. I have a special surprise for you.