Despite my issues with institutional Buddhism, I did pick up some very useful tools in my studies. One of the big things I remember from reading What the Buddha Taught is that Buddhism takes a different approach to its teachings than Western religions do, at least in theory. In a recent post, I paraphrased Michael Shermer in saying how if you don't believe in Jesus's literal existence, death, and resurrection, you can't really consider yourself a Christian.
However, if it were possible to scientifically disprove that Siddharta Gautama (the man who became the Buddha) ever existed, most Buddhists probably wouldn't stop practicing their religion. In What the Buddha Taught, Rahula says that Gautama's literal existence is completely beside the point. The point is that the teachings are there for us to follow.
Or not to follow. Buddha actually told his disciples not to believe what he was saying just because he said it. He encouraged his followers to test his teachings against their own experience. Rahula uses the illustration of claiming you have an object hidden in your hand. As long as I can't see for myself, I can choose to believe or doubt you. In other words, it's a matter of faith. But if you open your hand and show me the object, it's not a matter of faith because I can see for myself. For someone raised in an evangelical Christian background, the idea of a religion that allowed for and even encouraged a healthy level of skepticism was huge. Even though my skepticism turned out to extend to a lot of Buddhist teachings, I still admire and use that approach.
The other big idea I took from Buddhism was that of being in the present moment. I know that's not unique to Buddhism, but that's where I first encountered the idea. Like anybody else, I'm prone to get stuck reminiscing about the past or speculating about the future. And I wouldn't say that people should never do those things, but probably that most people do too much. Focusing on the present moment via meditation or other means helps pull me out of the whirlwinds of over-speculation.
For those of you who have left a religion, are there certain principles you still find valuable, despite rejecting the religion as a whole? What are they?