What is God?

[Mr.wizard]

They're called deists. The difference between saying "I don't know", and "Because god", is that usually the ones who say "because god" expect you to respond by worshiping that god. And might threaten to harm you if you don't, or if you try to use science to find the real reason.

The islamic god is a theistic god, so you would still be a theist.

Hmm. "I don't know" seems far more better than "Because God".
If i respond "I don't know" to whether i believe in a God or not,what does that make me?

You would be an atheist, if you have not accepted the claim that a god exists. The certainty of your belief has little to do with it, because not accepting the claim "god exists" is not the same as making the claim "god doesn't exist". If someone makes the claim to you "god exists" and you say "I don't know about that, can you prove it?" then they have not met the burden of proof for their claim in order to convince you to believe, and you are an atheist.