The purpose of logic faculty in us

One comedian once said: "I really tried to have the faith (that the earth was created in 7 days), but...I have thoughts, which can really xxxx up the faith thing".

If we are created, why would we be given the capability to reason well enough to deny our origin? If the design is perfect, every bodily part has its own function and purpose. Our eyes enable us to see, ears to hear, and a brain to know, learn, and reason. Sometimes things are not obvious to our sensory organs, like air molecules or microwave. But over the course of human civilization, we learned through the logic faculty in our brain to use tools to detect things invisible to our eyes or inaudible to our ears. Therefore the purposes of eyes and ears are once again fulfilled.

Overlooking all major world religions, there are still a few questions that demands better answers. For example, the purpose of existence. Why was the universe created? Some people would say: "Oh, I don't attempt to second guess His purpose". But can we even if we try? We are created because our creator is bored? Or is He/She lonely? Can we reach a reasonable conclusion? At least I haven't thus far.

Some other people would say: "Oh, you don't have to think too hard, just take a leap of faith". But why should we give up something which is given by our creator and which is perfectly purposeful and functional in order to take on faith about our creator? I think there is something wrong there.