Agreed; Russell in his radio debate with Coplestone makes this point very well. Of course there is a darkness here; if we accept that this is true of religious belief, what about other - apparently rational - beliefs?
I accept it is true about beliefs in general.
I was an atheist before I came here. I knew a few more things about the bible than your average churchgoer and I had a pretty solid understanding of eastern religions. So what I got from this forum
was a much more skeptical outlook and an awareness of my own magical thinking. It helped me be open to the fact that I hold some stupid ideas which do not correlate to reality. It helped me identify a few of them and honestly confront them, even though in all cases, I did not want to. I wanted my beliefs to be true. Now, I want to believe what is true.
This is not to say that I am free of magical thinking or stupid ideas. Just that I am aware that they exist and I think I am more likely to confront them. I think it is a skill, which with practice, people can get better at doing.
It may well be most, or even all, of our reasoning is post hoc!