Okay guys (and gals) the OP asked a serious question and if you object to it, you should at least be creative and say something like "I haven’t seen God, but if you brought him around, I’d be happy to photograph his for you for free".
On the otherhand, you have to remember that you cannot prove a negative, only disprove a positive. So, while you may not believe in God, you cannot prove he does not exist, so there.
God is a matter of faith. I believe in God. I have never seen him but I do not need proof. I also believe that NASA landed men on the moon, although I wasn’t there to witness that, either. Lots of what you think you know, are really things that you accept on faith. Evolution — show me the live animals. Dinosours, produce one for me. Have you ever seen an electron? How do you know your spouse loves you? You accept it on faith.
Anyway, none of this helps the OP, who wants a picture of an angel. I have never used a stock agency. In fact, I don’t know if they are honest or reputable or anything else. I’ve read their info for photographers, and I don’t believe it, but I guess some do. So here’s a link. There are others.
http://www.bigstockphoto.com/search.php?photo_name=angel& ;x=0&y=0 Don’t consider this referral an endorsement. I have NOT used them and have no experiences with them. Buyer beware, etc. etc.
Good luck. If you find God, please send him over.