Equal Rights

I just read a post on Facebook discussing why Christians are opposed to homosexuality and equal rights. It made me kind of angry. I don't understand how this is still an issue. After everything this country has gone through (ie. Civil Rights movement and women's equality), how is it that there are still people without equal rights? I'm not a lawyer, but the issues seems pretty simple to me. Religious people are morally opposed to same sex marriage but the United States has separation of Church and State, which takes care of them. Under the constitution all men are created equal (which was later ratified to mean men, women and African-Americans), so if everyone is equal under the law, why doesn't everyone have the same rights? I really can't wrap my head around it.