If Qur'an is not a valid source of Islam, I don't know what is.
We're not talking about a source of Islam, we're talking about a source of knowledge of the way things
really are. Let's say I go to the library and I see three books: Qur'an, the Bible and Harry Potter. All three books tell wonderous tales of magic and miracles, yet two of the three say their stories actually happened as described, as well as that I need to change the way I lead my life because of them (-Or else nasty things will happen to me after I die!).
Now could you kindly explain to me why I should believe one of these books is telling the truth? They explain how the world came to be (-God did it!), but science books can also explain that - and science in general is credible since it backs what it says with evidence.
Oops, i should know better, this debate never gets resolved...
However, I wonder if you would do me the curtesy of answering: Why believe in God?
Pretty sure I already answered that: Because I want to. I doubt there is any way I could justify it that would satisfy you though.
But if you believe it's true that doesn't make it true. Could you make youself believe 1+1=3 if you'd want to? Now when I can see that something is red then I simply won't believe it's green, even if it would be more convenient for me if it
were green (-Nope, the bank account isn't in the red...).