I had a nominal Protestant background. I attended about a dozen church services during my childhood, all before the age of 13. They were mostly charismatic pentecostal services, though one or two were Baptist. I became an atheist around 13 years of age. Though I don’t think the term had yet been invented, I was probably of the New Atheist mentality. Over all, very hostile to theism and religious belief.
I started to doubt my atheism about 17, attended a few masses, and eventually said a Protestant “sinner’s prayer.” It didn’t have a huge impact and I reverted to a milder nontheism for awhile with a liberal religious bent. By this point I was in no way impressed with any of the arguments for atheism. I had very little knowledge of theistic arguments. I guess you could say I had settled on a soft agnosticism.
Then I heard about Simon Greenleaf and discovered apologetics regarding the resurrection of Christ. Over all, I became very impressed with the strength of the case for the resurrection. I considered a couple of different denominations but I had always, even as an atheist, possessed a strong attraction to Catholicism. I started attending mass again, went to RCIA, and was received into the Church about five years ago.