John Brockman (virtually) gathered a group of "great thinkers" and asked them a simple question: What do you believe that you cannot prove to be true? The results are compiled in the book What We Believe But Cannot Prove.
It's a great question, even if it is scientifically wrong. Science believes we can't prove anything, we can only disprove hypotheses. The more times we fail to prove a hypothesis wrong, the more likely it is that we have stumbled upon the "truth." Of course, we reserve the right to prove ourselves wrong at a later date.
Given that most of the responders were scientists there were a fair number of there is no God/ no meaning to life type answers. Showing the inherent bias of the group sampled, only one brave soul stated a belief in God. Most of the responses, however, grouped around the existence of life other than on Earth (both for and against) and a wide variety of physics topics that frankly, I barely skimmed through.
My favorite entry was written by Kai Krause. He doesn't believe in Zen, living in the moment. He instead believes that the best moments in life are those spent remembering "back then" and anticipating what's coming next. He makes a really good point. Yeah, it's good to be present in the moment, but isn't the anticipation of the first kiss always better than the kiss itself?