The two main theories of how we started are evolution and creation. Creation, like religion, is based mostly on faith.
Evolution is based mostly on observations and evidence.
Since I've already decided that I will prefer logic over faith, I have chosen evolution. I too have chosen evolution but IMHO all things still go back to God, The Source Of All. Personally I prefer the spiritual path over the religious path. I didn't find God in the bible, I found God through meditation.