Religion is basic to human existence...

Catholics (at least some of them) believe in the organized religion of Catholicism. As such, that means that they believe in a long-established set of social and cultural traditions going back almost 2,000 years, which they have usually acquired from their families and their communities. So what's unusual about that?

Muslims are much the same. So too are Buddhists, Janes, Taoists, Confucianists (that's a philosophy), followers of Zen, Protestants of many denominations, Jews of various varieties of Judaism, etc....

It's a question of being born into a social fabric and assuming that it is normal, that's all. People generally do that.

Then you have the modern atheist. He practices a somewhat new religion, based on different perceptions of reality...and he worships ideals and "gods" that make sense to him. In doing so, he stands upon what makes HIM feel secure in an insecure World. What makes him feel secure may be: his own individuality (rugged individualism), his survival skills, his ego, money, property, reputation, fame, acquired knowledge, a law degree, etc....ad infinitum.

He is actually worshipping some of the "false gods" pointed to in many religious texts, but he doesn't realize it, that's all.

Everybody is religious in their own peculiar way.

If you ask why people need religion, you might as well ask why they need music, or hairstyles, or clothing styles, or politics, or philosophy, or logic, or any other common thing that people have.

Everybody does a whole bunch of things in an automatic way, not knowing why they do, mostly because they saw and heard other people doing it while they were growing up! That's what's so funny about it all. A philosopher is someone who notices how funny and arbitrary it all is and talks about it. Most people are too busy or just plain oblivious to bother with philosophy.