The great religions are also, and tragically, sources of ceaseless and unnecessary suffering. They are impediments to the grasp of reality needed to solve most social problems in the real world. Their exquisitely human flaw is tribalism. The instinctual force of tribalism in the genesis of religiosity is far stronger than the yearning for spirituality. People deeply need membership in a group, whether religious or secular. From a lifetime of emotional experience, they know that happiness, and indeed survival itself, require that they bond with others who share some amount of genetic kinship, language, moral beliefs, geographical location, social purpose, and dress code — preferably all of these but at least two or three for most purposes. It is tribalism, not the moral tenets and humanitarian thought of pure religion, that makes good people do bad things.

every religion preaches the truth of propositions for which it has no evidence.

primitive religions are based entirely on fear

I think all the great religions of the world - Buddhism, Hinduism, Christianity, Islam, and Communism - both untrue and harmful. It is evident as a matter of logic that, since they disagree, not more than one of them can be true. With very few exception, the religions which a man accepts is that of the community in which he lives, which makes it obvious that the influence of environment is what has led him to accept the religion in question.

Each person has his religion and sect impressed upon him as a child, merely as a prejudice, through memorized formulas that are not understood and a drilled-in fear of damnation.

All religions are based on obsolete terminology.

Religious belief is without reason and without dignity, and its record is near-universally dreadful.

Change is impossible in a religion that thinks it’s seen the last prophet. Prophets come and go, and we have to change with them

The problem with religion, because it's been sheltered from criticism, is that it allows people to believe en masse what only idiots or lunatics could believe in isolation.

Unfortunately a religious group defines itself foremost by its creation story, the supernatural narrative that explains how humans came into existence. And this story is also the heart of tribalism. No matter how gentle and high-minded, or subtly explained, the core belief assures its members that God favors them above all others. It teaches that members of other religions worship the wrong gods, use wrong rituals, follow false prophets, and believe fantastic creation stories. There is no way around the soul-satisfying but cruel discrimination that organized religions by definition must practice among themselves. I doubt there ever has been an imam who suggested that his followers try Roman Catholicism or a priest who urged the reverse.

It is here that almost all religions go wrong. Their priests try to make us believe that they know more about the unseen world than those whose eyes are still blinded by the seen, can ever know--forgetting that while to deny the existence of an unseen kingdom is bad, to pretend that we know more about it than its bare existence is no better.

Religious faith is the one species of human ignorance that will not admit of even the possibility of correction.

One of the problems with religion is that it creates in-group loyalty and out-group hostility, even when members of one’s own group are behaving like psychopaths.

Most religions, and certainly the Abrahamic ones, have three features that are foreign to science. The most important is religion’s linkage to moral codes that define and enforce proper behavior, behavior supposedly reflecting God’s will. The second is the widespread belief in eternal reward and punishment: the notion that after death not just your fate but everyone else’s depends on adherence to conduct mandated by your religion. And the third is the notion of absolute truth: that the nature of your god, and what it wants, is unchanging. While some believers see their ability to fathom God’s nature as limited, and don’t accept the notion of a heaven or hell, the certainty of religious dogma is ar more absolute and far less provisional than the pronouncements of science.
This combination of certainty, morality, and universal punishment is toxic. It is what leads many believers not only to accept unenlightened views, like the disenfranchisement of women and gays, opposition to birth control, and intrusions into people’s private sex lives, but also to force those views on others, including their own children and society at large, and sometimes even to kill those who disagree.