You can check this very easily as I did as a child: You can do a dozen or hundreds of prayers and then note down if your prayer changed anything. Write it down and count how many prayers really had any effect.

In my case nobody listend and the only success was: I saw a falling star after a lot of prayers that I wished to see one. But this was coincidence because lots of falling stars went down at this time.
Though I have to admit that a person really in need to believe in something could take such events as a sign.

Some researchers did the same with several groups of test persons. Prayers did not have any significant effect.
If you still believe, then it is all this: blind believing.

But in the end we all believe in something, in our kids, in our strenghs in our morality whatever. So I think it is not that bad. But it is bad if you kill other people for not believing in the same. And it is not very smart to be convinced that you have the one-and-only best-of-the-best objective to believe in.
There is a lot of variety and that is good. It makes this world colorful and interesting. We should not change this.