I'm not sure if "hate" is the right word, but if we go with
@adrian009 's "contempt" instead, that would be a fair description of what happened with me.
I went into things hoping and expecting that theists had good reasons for their beliefs even if they weren't apparent to me. I even started a blog where I tried to visit different religious groups the way that travel writers visit other countries: my plan was to find the commonalities that they shared with me, and where we differed, find unique gems that could be celebrated.
Instead, what happened was that as I talked to theists and explored their faiths, I found the experience draining and isolating. When I looked under the surface, I found nothing of substance in any belief system that I examined... and the believers didn't seem to care about their lack of substance.
Meanwhile, believers use their unjustified beliefs to justify all sorts of harm and ignorance.
I went into this with good intentions, but at this point, I'm just trying to avoid complete contempt for religion.