Unregistered

The short answer to your first question is that it was an intellectual journey that lasted about two years. During that time I learned about topics in psychology, biology, and skepticism in general which after some time caused me to turn a critical eye on my own faith. Eventually I left the faith behind.

Your second question is the easy one. I would just say that my feeling of oneness to God's economy are my own feelings. Perhaps they were profound and "spiritual" but its just an experience. I can still reproduce it today if I want. Or I could have a similar sensation meditating in a non-theistic way. Our brains are capable of producing these types of experiences. I don't see this at all incompatible with a materialistic, atheistic worldview.