you said, "I was shocked. There is clearly a double standard here, and we're really upset about this. They said the reason we can't wear 'Straight Pride' shirts is because they are disruptive. And I can understand how maybe some people were intimidated by the shirts with the Bible verse. But I don't understand how some students are able to wear 'Gay Pride' shirts while we can't wear shirts that just say 'Straight Pride.'"
if the shirts you wore to school just said "straight pride" on them, they'd be controversial, but i agree that they shouldn't be banned, at school or anywhere else. the problem is, you are twisting the facts. the shirts people at your school were wearing didn't just say "straight pride". they had a few other words on them as well...that "bible verse" that you ever-so-tactfully say may have "intimidated" people.
the last time i checked, the "gay pride" shirts that people may have been wearing to your school (or anywhere else) didn't also have on them some quote on them about how men who lie with women should surely be put to death.
things like trying to start a conversation about your religious beliefs as they apply to sexuality, or taking pride in your sexuality, are one thing. however, responding to a student-organized week against sexuality-related bullying by wearing a shirt that says that gays should be put to death is another thing: specifically, an example of the kind of bullying that needs to come to an end.
queer students and their allies aren't running around trying to make you feel subhuman because you happen to only be into people of the opposite sex. give them the same ounce of respect.