A comprehensive survey revealed that only about 14 percent of English speaking professional philosophers are theists. Most professional philosophers regard it as a strange aberration among otherwise intelligent people. Surveys of the members of the National Academy of Sciences, composed of the most prestigious scientists in the world, show that religious belief among them is practically nonexistent, about 7 percent only.
In the European Middle Ages belief in a God was ubiquitous, while today it is rare among the intelligentsia. There has been a dramatic change in the last few centuries in the proportion of believers among the highly educated in the Western world.
I genuinely find the gods of religions like Christianity, to be less plausible than, say, Father Christmas. I'm astonished that people can believe in such stuff. Why people still believe such stupid stuff?
Indoctrination into Religion:
People tend to stay with whatever religion they were raised in. People acquire a religion before their critical thinking skills develop and that religion become the true religion for them. That's really not a very good reason to believe the religion is true.
Indoctrination into Anti-Atheist Bigotry
Many societies think that those who don't believe in god are evil, immoral, and a threat to the society. And consequently the people never dream of dropping their religious belief. Who wants to be regarded as immoral? American Children learn in public schools that USA is a nation for people who believe in God and this message is reinforced throughout their lives by preachers, politicians, and all community leaders.
Religion seems to be enormously important to families and communities, creating a tremendous amount of pressure on individuals to conform to religious practices. People who step out-by choosing to live different- are perceived as rejecting one of the most important bonds which keep a family together.
Fear of death-cessation of existence- is a nightmare for many. They subconsciously long to live forever and hence afterlife appeals to them emotionally. And they insist on believing that somehow their soul or mind will continue to exist eternally in heavenly bliss. Some believe they will be reincarnated in a new form. They all want to believe that physical death is not the end of this life.
Many conservative believers from many religions seem to be happy that there is a god who wants them to exercise unchecked power over women. This seems to be the real reason why some men cling to their religion. As their scripture is clothed with divine authorship it is believed by the women too.
Some other reasons:
Religious beliefs make it possible for believers to avoid taking personal responsibility for what's going on. They don't have to be responsible for ensuring that justice is done because God will provide that. They don't have to be responsible for solving environmental problems because God will do that. They don't have to be responsible for developing strong moral rules because God has already done that.
Believers Lack basic skills in Logic and Reasoning. They are blind to reason; their faith swallows every reasonable thought or argument. There is no reason to believe in a god. Perhaps the most basic reason for not believing in any god is the absence of good reasons for believing. Those who believe must find support for their beliefs, not the other way round. Non-believers don't need reasons not to believe.
Just think: Why does the theist disbelieve in all other gods except the one or a few of their own religion? There have been tens or thousands of gods throughout history. Why believe just in those of your religion? Many of the gods are already dead. Some of them still live on, but they will die too eventually.An atheist simply doesn’t believe in any god. He is not interested in denying any god. Atheism is nothing more or less than the absence of belief in gods. Living an atheist is difficult as a vast majority in the society think poorly of atheists. Atheism does have an advantage over theism as theists are unable to provide good rational, logical and empirical reasons to believe that their god exists. Their Belief is decided by circumstances, family and early childhood experiences.