Your age isn’t important. I do find it somewhat unlikely that someone who has dabbled in every form of cult and occult and ended up a strong Christian was ever really an atheist.
During your atheist period, what books did you read?
Dawkins was a favorite author. Demon Haunted World by Carl Sagan.
Ayn Rand...Atlas Shrugged, Fountain Head...
I haven’t thought about atheist books for several years. It may take some time for me to remember. I’ll go through my books at home and see if I can find others that had specific impact on me.
Even though it isn’t specificly athiest, Elie Weisel’s “Night” made a very large impact on my disbelief about God.
A book I read a very, very long time ago (probably the first atheist book I read) was Psycho-cybernetics. Opened my small-town Mormon mind in a huge way.