Over the last century, throughout different parts of the western world, Catholics were denied equal treatment before the law; Jews were institutionally discriminated; black people were regarded as racially inferior; women could not vote for fear that they would become masculinised. As for marriage issues, African Americans could not marry white people because it was against the word of God, and the same was true for gay marriage.
And even though all of these horrendous inequalities and inhumanities were carried out under a religious mandate (a force which is still to be reckoned with in some societies), there are scholars who, thankfully, find reasons to be optimistic about the future of human civilisation. To quote Michael Shermer, publisher of Skeptic magazine and and a Presidential Fellow at Chapman University,
“I like to paraphrase Winston Churchill in his description of Americans: You can always count on religions to do the right thing…after they’ve tried everything else. It’s true that the abolition of slavery was championed by Quakers and Mennonites, that the civil rights movement was led by a Baptist preacher named Martin Luther King Jr., and that gay rights and same-sex marriage were backed early on by some Episcopalian ministers. But these are the exceptions, and for the most part people who opposed abolition, civil rights, and gay marriage were (and still are, in the latter case) their fellow Christians. […]
The gay rights revolution we’re undergoing right now is a case study in how rights revolutions come about, because we can see who supports it and who opposes it: The vast majority of conservative and fundamentalist Christians have opposed (and still do oppose) same-sex marriage and equal rights for gays, whereas secularists and non-religious people support the movement; and those religious people who do endorse same-sex marriage are members of the most liberal and the least dogmatic sects.
So, while I acknowledge that many religious people do much good work in the world, manning soup kitchens and providing aid to the poor and disaster relief to those in temporary need, religions overall have lagged behind the moral arc, sometimes for an embarrassingly long time.”
“At every turn [the religious] try to make the public forget about their earlier obscurantism, in order that their present obscurantism may not be seen for what it really is.” – Christopher Hitchens