When I was 24, after six years of soul searching I came to the conclusion that God was a figment of mans imagination. When I say God I mean the god that watches over us and cares what we do and judges us. I went through a process of breaking every taboo I could think of. The first thing I did was turn on a light on Shabbat. Next I ate bread on Passover. I tried pork (didn't like it at all), and shellfish (ewwwwwwww). The big test was eating on Yom Kippur. I had been fasting on Yom Kippur for 14 years already and half expected to be struck down by lightning when I did it. I had to force each mouthful down. By the third year I wasn't even thinking about it.
For years I shrugged off every ritual and symbol and Judaism.
When I moved back to the US something inside me changed (see my post "Does it Matter?). I started looking for other Jews and decided to take a course in Jewish Mysticism to fulfill my humanities requirement for my environmental sciences degree. I had never studied Jewish Mysticism growing up. Tanach, Mishna, some Talmud and Jewish Philosophy were the mainstream areas of study. This was also the first time I studied Judaism in a secular setting. It was disconcerting in some ways.
The course opened up a new interest in Judaism. I realized that I could study Judaism without having to "believe". I also realized that I wanted to do it. Judaism is so complex and it's a huge part of who and what I am. My family for the past few hundred years were all Hassidic Rabbis. Reverence for study and a thirst for knowledge is ingrained in my genes.
This is part of what made me who I am today and learning it from that point of view is fascinating. Every now and then I'll come across something that makes me ponder whether there is a God (but like I said not the judgmental overbearing one) and what part this "God" plays in the Universe. But every time I think I found something I can believe in I find holes in the logic. Oddly enough it's my Jewish upbringing that makes me crave logic in everything.
I'm still going through the process and I'm still Agnostic.