In Case You Were Wondering, There Were LGBT and Non-Christian Students at Hogwarts, You Just Never Saw Any of Them

In response to a question about whether or not there were any Jewish students at Hogwarts, JK Rowling not only named a Jewish student who attended with Harry named Anthony Goldstein (if you're wondering, he was in some bits about Dumbledore's Army), but also confirmed that there are LGBT students, and people of all religions except Wiccans in attendance.  

So, they're there, just not really where you can see them.