Every person with a religion believes that their religion is the right one. If I didnt believe that Islam was the truth, I wouldnt be Muslim. And if you didnt believe that Christianity was the truth, you wouldnt be Christian.
I do have a problem with Angels having free will…simply because Angels are involved a lot in revelation. In any case, its a minor point. You believe that there are demons, yet what are demons? Are they Angels gone bad? In Islam, its pretty clear.
Barton says:

No, no, no. None of us believe that jinns are anything but the most horrendous and evil devils - we would rather be dead than to even talk to one! Check it out! :bigyikes:
That argument doesnt always work. Say you are talking to a hindu (many of the Hindus I know say they believe in ONE God and get very offended when someone says otherwise)…what will your argument be with a Hindu? If God can be trinity, then surely he’s complex enough to be 100 persons in 1.
The idea is that Muslims believe that God is not a unity of things…He’s just one, unique. He begets not nor is He begotten. This idea is what separates Islam from every religion in the world
Just because its not the account thats found in the Bible, doesnt make it false.