Why am I Buddhist? The short answer is that Buddhism works.
The long answer is the same but takes more words. I was brought up as a Christian. When I hit my teens I dropped religion and switched to atheism. That was mainly because I objected to the rather too common, "anyone who does not agree exactly with us is damned for eternity, especially those heretics in that church down the road," attitude I found. After a few years I moved away from atheism, I felt that while it did avoid many of the problems with Christianity it was not itself a solution. I looked at different religions to find something that would work for me. None of the Abrahamic religions attracted me – as a hangover from my atheism I still had a problem with the concepts of God and soul. Initially I was interested in Hinduism. The background of Indian religion provides a very different world view: less exclusive – everyone achieves liberation eventually, the concept of karma and a much more relaxed attitude to both other religions and to alternative variants of the same religion. Of the Hindu texts the Bhagavad Gita and Patanjali's Yoga Sutras were the ones that attracted me most. In particular there is hardly any mention of gods in the Yoga Sutras. That seemed to be an interesting direction to explore.
Reading round Hinduism I inevitably came across Jainism and Buddhism. Jainism has souls but no gods, or at least no important gods. Buddhism has no souls and its attitude to gods is very casual – like any other living being they need to become enlightened. A mere god is far inferior to a Bodhisattva, let alone to a fully enlightened Buddha. Buddhism seemed to have the elements I was looking for: non-exclusivity, no soul, morality and while it did have gods, they were unimportant and could easily be ignored. So I tried Buddhism. I studied more on it, went to groups and to meditation classes and found that everything fitted together well and it suited the way I wanted to go.
A frequently quoted Buddhist text is the Kalama sutta
which says that if we are to accept something then we have to try it first to check that it is correct:
[The Buddha said:] "Kalamas, when you yourselves know: 'These things are good; these things are not blameable; these things are praised by the wise; undertaken and observed, these things lead to benefit and happiness,' enter on and abide in them."
This advice applies to the Buddha's own words just as much as to anything else. I followed the Buddha's advice. I tried Buddhism, found that it worked and I have followed it ever since.
There is even some scientific evidence that Buddhism works: see Buddhists 'really are happier'
Buddhism is a very practical religion. It is a sustained attempt to alleviate the suffering of a less than perfect world. Generally it succeeds. Buddhism works.