At the risk of being "that guy", it has to be said that this kind of study is unreliable. Posting a bunch of messages to r/drugs and r/psychedelics to come take their survey is going to suffer from all sorts of statistical biases. It is still better than the lowest for the study, the sample size of one: "Well this is what I experienced". Yet here I go. I have always been a materialist, and I've also never done drugs…
No matter how much you felt like you were in the presence of the Light, it didn't change the fact that the Light doesn't exist. It was just a trigger in a part of your brain that can bring on neurological changes in many people.
I'm not an atheist because I want to be or because I haven't had spiritual experiences. I'm an atheist because facts and logic have led me to the unfortunate conclusion that this life is all I'll ever have and that when it ends, I have no belief that something else will continue for me.