I'm a Christian, but once I heard this paradox I was at a loss of words.
Christians believe God is omnipotent, meaning he is all-powerful. But can God make a rock so big that he is unable to lift it?
If he can't make said rock, that means he isn't able to create all things, so he is not omnipotent like people say he is. But if he is able to make the rock, that would mean he lacks strength, making him not omnipotent.
So no matter what answer you give, you aren't able to prove that God is omnipotent.
How would you answer this question if it was proposed to you?