One of the things the Bible is firm on is that God will be perfectly fair with everyone. No one will be judged unfairly for what they could not have possibly known. And each person's judgment will be exactly what it should be. So, no reason to worry. God knows everything and will not make any mistakes in this regard.

How can god send a person of non-Christian religion to hell when they never knew any different?

If god is so great and kind and then would he, for example send a boy who was raised Muslim and never knew any different to hell of he died?