Thanks for taking the time to share that with us. This is good timing, I have just been thinking about how weed may have played a part in my de-conversion.
I was very religious until I graduated high school, first time I drank was graduation day. I didn't start smoking weed until I was already two years into college, which was a christian school (I was getting a Biblical degree). I had been assigned a final presentation on a topic we disagreed with, I picked cannabis, and was persuaded to give it a try after months of research.
I had also been dealing with depression since I was young (I was diagnosed at 12) and had not found any real ways of dealing with it yet. By the time I tried weed, I was desperate to try anything that could potentially make me feel better. Took my first hit, and BOOM. I was the happiest person alive for the next few days.
About a year later I got a medical card and started smoking more regularly, about this time I was pretty deep into my Bible degree and I was having a harder and harder time making sense of any of it. I had always been desperate to find the one really true piece of evidence that would show everyone (and myself) that it was all true. The more I studied, the more holes I found, the more I saw that the whole thing was a house of cards. I had found a sliver of hope in something my professor aptly called "Synthetic Theology" which attempts to embrace the discontinuity as a way preventing narrow minded worldviews. That was the final straw that held it all together for a few more months before the cognitive dissonance set in and the absurdity of it all became apparent. Not only had my theology been synthetic, my whole belief structure was as well.
It wasn't overnight, but as time went on I began to see the whole thing as an outsider and found eventually found myself an atheist. This, of course, made graduating college a little difficult. Since I was so deep into that school and that degree, my only viable option to was to walk away with an overly broad degree in philosophy (which has just been great for the job search).
Anyway, my disbelief came about around the same time that I began using cannabis, and the opening of the mind as a result of cannabis could certainly be a good explanation of that. Now, one thing to note is that although my depression had gotten better overall since my deconversion, it has not disappeared. It is still something I deal with regularly, and I am the first to admit that I still have not really found a great long term solution yet, but it is always a work in progress. Send me a PM if you need someone to talk about this stuff with.