Joining an organization and not being religious

I have been told by several friends in other GLO's that you wouldn't enjoy ritual if you aren't Christian. One of my closest friends, also an atheist, disaffiliated with her organization the day after initiation because she was so offended. The initiation was at a church and involved them having their hands tied to a Bible and kneel at the alter to swear their allegiance to AAA sorority. I am a Christian, and my sorority rules make it clear that in no way is any part of ritual to be interpreted as any type of religious activity. I don't understand why people would stay for a ritual that involved this. If I would have walked into that room and found out I had to get in a coffin, kneel at an alter, etc. NO WAY! I would've been first one out the door. But I guess for some people they don't want to "get in trouble" with the sisters for leaving. I enjoy being greek, and I am loyal to my organization, but not so much as to be disrespectful to my faith.