Is it right to call a believer rational even if she cannot prove articulately or give good arguments for her belief in God? Let's just say I ask a believer "Why do you believe in God?" and she simply answered, "Because I've experienced God's grace in my life," and she needs no arguments or other evidences for her belief, is her position justifiable? I personally thinks it is but if that is the case, then what would make belief in God irrational, if simply certain personal experiences can justify such belief?

If she had reasons to believe, it would not be faith that she had but knowledge. It might be hard to set up experiments and prove that love exists, and yet I would not call a person who believed in love on the basis of personal experience - irrational. Perhaps it would be irrational - to think- to imagine - that reason could take in the full sweep of reality. It might be reasonable to believe that there are limits to reason and yet as human beings we still have to decide whether or not believe in what falls outside the bounds of reason. Thanks for your provocative question.