It's absolutely not a myth. There are people that stand out front of the student union and tell everyone they are sinners and going to hell. And there are also the LGBT groups that try to raise awareness for their views. There are a good number of religious organizations and a fair number of the "equal rights" organizations.
Knap gave you a perfect example of how tolerant college is. College is overflowing with different view points and beliefs. If you're not forcing your views on anyone you will be overwhelmingly accepted. In my time at UNL I hung out with pot smokers, boozers (or college kids if you will), other drug users, hardcore Catholics, moderate Catholics, Bereans, Lutherans, Jews, Muslims, Atheist, and general "non believers". And you know what, we all get along pretty well and know how to have a good time. That doesn't mean we didn't have the occasional philosophical/religious discussions that could get pretty heated, but in the end you just have to agree to disagree. That doesn't mean you can't still be friends though.