Oh come on. They called out to the God they worshipped in life, just like you would.
You don't seem willing to admit to the unpleasant things that follow from Scripture. It's easy to cheer an Arafat or Hitler going to Hell. It's not quite so easy with the Khmer victims.
I don't know that the two criminals hanging on either side of Jesus Christ of Nazareth had ever been religious, except perhaps to worship their own lusts, but one rejected the Savior and the other cried out to Him for salvation. I cannot explain it, except to say that God says in His Word that He puts a knowledge of Himself in the heart of every man. I encourage you to read the first chapter of Romans, beginning at verse 19.
Jesus Christ of Nazareth spoke much more about Hell than He ever did of Heaven. His dire warnings are crystal clear and would only be dimmed by my attempts to explain them.
Suffice it to say, Hell is a place to be avoided.
Psalms 111:10 - The fear of the LORD is the beginning of wisdom: a good understanding have all they that do his commandments: his praise endureth for ever.