I was 18 and had spent a few years as an evil atheist. I was in a small Pentecostal church someone I met invited me too. I guess I was just really curious and looking around. The church was mostly old people and their children (mostly younger than me). I was really messed up back then, still kind of an awkward teenager. I had really bad social anxiety and was always nervous in public (God actually delivered me from that years later but that's another story). Anyway, I was standing while hymns were being sung, and someone came up behind me and put a hand on my shoulder. I assumed someone decided to pray for me and just let it be even though I was constantly nervous and uncomfortable being touched. Then I turned to look to see who it was, and there was nobody anywhere near me. That was that. It was another day when I received the Spirit of God, and the experience was so intense. Atheism was no longer going to be an option at that point.