Sorry but I can get back to your other points but wanted to clarify. You know islam is bullshit, and thats the truth. But you are not sure God exists? If he does exist wouldnt you concede it would be beyond you to constrain what god is or isn't and therefore Islam could be 'his religion' you can't know it is not. That aside from the fact that your negative presentation of the Abrahamic god is contested.
Even if any sort of gods existed, there is nothign to say that they would even be Abraham's invisible friend. What if the divine that existed ended up being Oya and Yemaya and Obatala? Or Krishna and Ganesh? Or Loki and Freya? Shit, what if it was all of them? Hey, any of these religions could be true, and you've gone atheist on all these other gods and only limited yourself to one choice.
Or none of them could be true, which seems most likely.
(Also, the bible - and the quran - do a fair job of presenting Abraham's friend in a negative light. He doesn't need atheists to do the job for him).