If suffering can never be eradicated, our purpose must account for suffering.
Our purpose must make the pain worthwhile or meaningful. If not, life, suffering, and pain are all absurd.
In a moment of clarity (seeing the absurd), we can see the religious/humanistic impulse to validate suffering is attractive (giving meaning to pain retroactively).
The leap is to trade up: swap the obvious irrationality of suffering for a portentous, impossible dream. Upgrading absurdities maintains purpose by excluding logic and, in so doing, secures comfort.