...And liberty and justice for some... (some being everyone that isn't black, Mexican, gay, trans, Asian...)

I'm just wondering, isn't America land of the free? And since when does religion control government into thinking which is right or wrong? America says that we are free and have equal rights, but blacks are still getting murdered because theyre black. Gays can't marry because it is "violatioting the holy sancety of marriage". I could go on and on. Can someone explain how religion and politics somehow managed to get intertwined?