Forum veterans, please correct me if I’m wrong on this, I’m no apologist.
There is a Catholic teaching known as invincible ignorance which basically says that if someone is not a Christian by no fault of their own (eg, maybe they live in a remote country and they have never heard of Jesus before) then they will not be punished for this (ie, won’t necessarily be sent to hell). This means that people of other religions and even people of no religion still have a way to get into heaven.
People who are not Christian by choice though (ie, they have been told about Jesus well enough that they have no reason to not believe other than their own choice to reject him) are guilty of a sin, rejecting Christ, and I think that those people go to hell if this is unrepented.