People sometimes have weird attitudes when it comes to religion - particularly if a non-"mainstream" belief system like Wicca is involved. It's not very mature, but it happens.
I've experienced a couple of religion issues...
When I joined my local sorority, I became the first and only non-Jewish member. My sisters were very welcoming, but I heard a few mutterings from others, and someone actually said to me outright, that I was only offered a bid so that I could be the token non-Jew.
(The guy who said that turned out to be a total pr!ck...)
One year, our president decided to schedule a chapter meeting on Easter Sunday. It was in our bylaws that no mandatory event, including chapter, could be scheduled on Jewish holidays (including the Sabbath) or on the major holidays of any religion practiced by an active sister or new member. There were several Christian sisters at the time. I asked her to move the meeting, and she refused. Had a big argument with her in front of the entire chapter. She offered to make it later in the evening - I had to explain to her that Christian holidays, unlike Jewish ones, do not end at sunset. Finally she relented and moved the meeting to Monday.
There is a GLO at my school that, I am told, requires new members to swear an oath by Jesus Christ at initiation. This doesn't go over too well with non-Christians.
But this is hearsay, as I obviously have not attended an initiation for this GLO.