There is an old Catholic doctrine called “Invincible Ignorance”. It reflects God’s desire that someone who had never heard of Jesus Christ, and did not try to avoid hearing about Him, could get to Heaven if he had led a good and upright life.
A few plan to use Invincible Ignorance in their own defense at Judgment Day: “I had heard of Jesus Christ, and heard about Him, but the evidence of evolution and all the humanist teachings that I have been brain-washed with have kept me from seeing how real He is. Though I am not literally protected by Invincible Ignorance, since I have heard of Jesus Christ, Invincible Ignorance is actually why I behaved the way I did.”
Catholic Fundamentalists can remove that argument in a couple of sentences. “God has the ability to program actual objects, structures, and beings. He programmed an actual universe in a week, and programmed the first human being in a day. That God sent prophets, and, finally, His own Son, to help you save your soul. You can choose to believe in a God that powerful, or reject that idea.”
Then, the Invincible Ignorance argument can’t be used. They have heard The Word, and a reason to take it seriously.
After that, they can only save themselves by actual belief and subsequent obedience. That will make the world a better place.
Get busy.