I hate to see it, but I think we're starting to see "alliegances" and people down-up voting based on who they like, who is their friend, who supports them and their beliefs, and who is the same label of Muslim -- whatever they subscribe to.
Don't DV the messenger, I'm just saying that this is my impression when I surf the site. I don't do this, I subscribe to Dynamic's methodology.
The user in question had a lot of low-quality answers initially which I DVed. He has some great ones which I up-voted. No issue here.
I have also seen a similar trend on my own posts -- some answers which I have +4, +6, +9 etc. suddenly get a -1 out of nowhere. When I check my reputation history, I see a bunch of DVes in a short amount of time.
Please, keep your personal opinions to yourself. Islam.SE is a site based on mutual tolerance and acceptance of "other" types of Muslims who believe things differently from what you believe. It's not a problem. Vote based on the authenticity and clarity of the answer, not on the underlying beliefs of the individual.