If Christians came to America to escape religious persecution?

Then why did they come to this country to become the exact thing they were running away from? In Salem 141 were arrested, 19 were hanged and one was pressed to death just for acusations of having another faith. Today, on here for example, certain people fuss that athiests and agnostics don't belong on R&S because of their 'lack of faith', that it should only be for Christians. Does this country's religious freedom mean nothing to some?