Technically, I haven't left Christianity. I still attend church, and I keep an open mind towards the religous rites I see, but I really don't consider myself a Christian. I'm more of an agnostic, with a slight deistic slant. Essentially, I believe that the Universe created and runs itself, but something had to start the ball rolling. But whatever entity that did that didn't stick around. We're on our own.
I started to lean that way, oh, nearly a year ago, during a comparative religons class I was taking in school. During the Christianity unit, I found out a lot about the early history of Christianity I had never heard before. I did a little bit more research, and found that the modern Christian religon was invented by the Romans three centuries after Jesus died. Early Christianity was very, very much different than the religion is today. Early Christians even believed in more than one God! So if that was the case, and Christianity hadn't stayed "pure" since it's inception during the life of Jesus way back when, why should I take it as truth? Christianity even assimilated non-Christian religious icons to use as it's own. Halos? Formerly known as Egyptian sun-disks. Christmas on December 25? A pagan winter solstice celebration. The image of God being an old white guy with a flowing beard? None other than the god Zeus, of Greek and Roman fame.
Once I was shaken out of my comfort zone, I began to see other things in my religion that bothered me greatly. Where once I had blissfully ignored the hypocrisy and hatred stemming from fundamentalist elements in Christianity, I was now painfully aware of them. Religion cropped up in debates ranging from school dress codes and Christmas to abortion and gay marriage, and it seemed to be the root of most of those problems. I wanted none of that.
That was the practical side of my "un-conversion." The spiritual side was much different. As I looked around at the world with my newly opened eyes, I saw things that no compassionate god could allow. Yes, I've heard the age-old argument that God punishes us to make us learn. But there is too much pain and suffering in the world for that to hold true. In Africa, children are often left without parents because of AIDS, a disease that some Christians say God created in order to wipe out homosexuals. What kind of sick twisted god do those individuals worship? AIDS kills straight people, too.
However, I wasn't about to become an atheist simply because I didn't see God's effect on our world. This is where the comparative religions class comes back in. At the beginning of one day about in the middle of the course, the teacher wrote two words on the board: theist and deist. He explained that the theist believes in an active deity, one that affects the lives of humans. Thus, one that doesn't believe in such a deity is an atheist, "a" being the Latin prefix for "non." The deist, on the other hand, still believes in a deity, but thinks, as my teacher put it, that "God whirled a top and walked away." I have learned since that was a fairly simplistic definition, but it struck my fancy nonetheless. The reason for this will come later.
I have often been fascinated by the way the universe fits together like clockwork. Everything is so perfect, that the odds of it all happening completely at random (and in a universe where random is preferred, no less), are practically nil. Of course, the rabid atheist will tell you that little chance is still some chance, but the probability of everything happening as it has without any external force is something along the lines of 10^123:1. Those are some pretty small odds. So, I reasoned that something must have influenced the universe in order to make it able to support life in all it's various forms. However, I don't believe the universe was created by this theoretical most likely extra-universal being, whom I tend to refer to as the Designer. No, instead I have a rather odd theory that the universe is like a gigantic computer program, with specific parameters set for certain events and occurences. The Designer would have created the program, but given it a rather unlimited degree of self-control, meaning the universe is it's own creation and entity, running itself, monitoring itself, all without the help of any external being.
Even believing all this, I probably could have stayed as a Christian. But here's the clincher: I don't believe anyone can ever truly know whatever god they worship. You may think you have a personal connection with God, or Allah, or the Flying Spaghetti Monster, but it's a connection your own mind created in order to make you feel as if you're a part of something bigger. The subconscious mind is more powerful than many people think. I also don't believe one can ever prove, nor disprove, the existence of God, in any form. All proof for God is manmade, and no concrete proof against God can be found.
And that, is why I am no longer a Christian. Call it a lack of faith, or call it whatever you will. I believe in the religion of reason and logic above all else, and it leaves little room for the kind of God other organized religions present.
The more you know, the less you don't know.