For since the creation of the world God’s invisible qualities, His eternal power and divine nature, have been clearly seen, being understood from His workmanship, so that men are without excuse. 21For although they knew God, they neither glorified Him as God nor gave thanks to Him, but they became futile in their thinking and darkened in their foolish hearts. 22Although they claimed to be wise, they became fools,…
Ephesians 4:18
They are darkened in their understanding and alienated from the life of God because of the ignorance that is in them due to the hardness of their hearts.
Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.
Blatant brainwashing (get them when young and malleable). As Rush says, young brains full of mush.