There are many reasons why. Let's see how many I can recall right now. First, religions give people a platform from which to convince themselves of lies. So they don't have to take responsibility for whatever they might do. They can just say "It's god's will" and leave it at that. Also, oppressors use religion as a way of controlling others for their own gain. Just like the leaders of any cult. They will prey on your emotions to gain control of you. Once they have done that, anything can happen. And at one point or another in any religion-cult, "anything" has happened. Sometimes frequently.
Also, throughout history there have been many religions. And all of them are different to varying degrees. You would think that if there was some actual "god" in control of things, all of those different religions would have gotten the same message. But they didn't. Also, though all religions suck, I will speak of christainity. Because I am most familiar with it. I have read the bible. And there isn't a single thing in the whole thing that is true. That is as far as the sciences are concerned. It was completely wrong about how life arose on this planet. And it didn't say a thing that was correct about geography. It didn't even mention anything about the lands of the Western Hemisphere. Which is about half the planet! Neither did say anything about geology that was correct. Neither did it mention anything about physics, mathematics, genetics, mocroorganisims or electricity. And anything it had to say about astronomy was a joke. I don't think they even knew what stars were. Basically it, like any other religion, is a religion for cave men.
Also, throughout history there have been many religions. And all of them are different to varying degrees. You would think that if there was some actual "god" in control of things, all of those different religions would have gotten the same message. But they didn't. Also, though all religions suck, I will speak of christainity. Because I am most familiar with it. I have read the bible. And there isn't a single thing in the whole thing that is true. That is as far as the sciences are concerned. It was completely wrong about how life arose on this planet. And it didn't say a thing that was correct about geography. It didn't even mention anything about the lands of the Western Hemisphere. Which is about half the planet! Neither did say anything about geology that was correct. Neither did it mention anything about physics, mathematics, genetics, mocroorganisims or electricity. And anything it had to say about astronomy was a joke. I don't think they even knew what stars were. Basically it, like any other religion, is a religion for cave men.