Do I let go?

Sometimes, letting go is for the best. I think you should consider the fact that she is merely a friend, and move on. Life is too short to dwell on things that we can never have. As the old song goes, "But, it is time to face the truth, I will never be with you".

So basically this girl I've liked for some time kept sending me mixed signals. I asked many times and she never confesses feelings so I let go of wanting her love love (she told me she loves me as a friend). However, I wanted to be friends and we were on social media. I said something about her beliefs and she unfriended me. Do I friend request her or leave it be? Did she act irrationally and not k a way back or do I just move on?

How much did she mean to you? Do you think it'd be worth it to keep talking to her? You could try adding her back once to give her a last shot, and let things go if she declines. If that happens you should have a talk and sort out the mixed signals, randomly blocking you, etc.

what did you say?

I think for my personal opinion If for her as well you are important she didnt need to act like that, and to discuss anything even something Maybe bother her thats the right thing, but for you better to move on dont spend time to something that probably not gonna change give all your efforts to someone that will come the right time properly and will see you the same way

Yes.
Best to let it go and avoid any further contact with her, unless she politely messages you.
It seems that the two of you do not have compatible personalities, beliefs or ambitions.

Yes, she only wants OP as a friend, so no romantic interest there.

On top of this, he made a religious comment the girl didn't like. Religion means a lot to some young people and the fact the she unfriended him means he didn't say the right thing and has lost even her friendship.

Some things just aren't meant to be.

I would move on.

We have the same religion just a slight difference of opinion. I gave her facts to back my argument on a certain matter and I wanted to discuss it but she was offended or something idk. I was respectful. I tried to be friends w her one last time but honestly I'm past it now it's up to her