Background: I believe that there was likely a creative spirit of some sort, or "God," that created the universe, possibly with the intention of having intelligent life develop. There are two main questions that science is unlikely to ever answer: 1) How did the universe come about?, and 2) Why is it that I, and presumably all humans and most animals, experience "consciousness," i.e. awareness of my existence. Hence I believe in a higher power that's beyond our understanding. However, while I believe in God, I no longer believe in Christianity or any other religion.
One of the realizations that led me away being a Christian is how contingent my being born Christian was on world events. There have been many spiritually enlightened individuals over the course of human history, some of whom created new ways of living and believing. Moses, Jesus, Paul of Tarsus (without whom we would never have heard of Jesus), Lao-Tzu (founder of Taoism), Siddharta Gautama ("The" Buddha, founder of Buddhism), Bodhidharma (one of the fathers of Zen Buddhism), and many more that we've never heard of. The reason the current inhabitants of the United States are mostly Christian is because the US was primarily a British colony. Britain, while initially "pagan," became Christian because it was a part of the Roman Empire. The Roman Empire was Christian in part because Emperor Constantius had a Christian wife (or concubine, history's not clear on this) who fathered his son Constantine, who, when he became emperor, was sympathetic to Christians since his mother was Christian. (Although it seems Christianity was gaining popularity in the Roman Empire pretty rapidly and probably would have become the dominant religion regardless of Constantine's tolerance.) The reason Christianity was able to spread through the Roman Empire was because Jesus and Paul were part of the Roman Empire. If Judaea had not been conquered by the Roman Empire, or if the Roman Empire had never developed, Jesus would likely have been forgotten. If China hadn't stopped most of it's maritime explorations in the 1400's, North America might have been colonized by Chinese rather than British colonists. If that had happened the US might be predominantly Buddhist. There are probably thousands of religions in the history of humankind, and certainly more than one of them has important things to teach us. The reason I was born Christian is contingent on many historical events. It's counterintuitive to think that only one religion, the one I happened to be born into, is the only right one. There is no rational reason that one should have faith in a single religion. It seems that the only way to be Christian and still maintain rationality is to take the viewpoint of my Christian friend Peyton Bowman: "It may not be rational to be Christian, but I choose to believe in it because I am a stronger and better person for it."