OK,then,you don't have to go.
Okay, so a while back, I did some research on the IDF and its rules of application for a story. The knowledge is a little rusty, but I believe this is accurate:
You can join the IDF if you are an Israeli citizen. You can maintain duel citizenship (US/Israeli) and can obtain Israeli citizenship most easily by converting to Judaism, specifically Orthodox or Conservative, aka right of return.
I do not believe there are any limitations on being in the IDF after being in USAF, but you would need to get Israeli citizenship and, if you're a big fan of Jesus, that might be a little trickier. I don't think you would have to renounce your religion to join the IDF if you were made a citizen some other way. There are non-Jewish citzens of Israel.
I would defend the land of my forefathers if not for a variety of medical issues that make me definitely unfit for combat.