Purgatory is a state of purification where souls are separated to any attachments and consequences of sin, since "nothing unclean can enter heaven" (Rev. 21:27).

Grave sin is always and everywhere wrong. It is especially eggregious when an abuse of power is involved, and innocent people are harmed by it.

"But if anyone causes one of these little ones who believe in Me to stumble, it would be better for him to have a large millstone hung around his neck and to be drowned in the depths of the sea. 7Woe to the world for the causes of sin. These stumbling blocks must come, but woe to the man through whom they come!" (Matt. 18:6)

Priests have consecrated themselves to Christ to care for the flock of God, and by sinning against the flock become wolves among the sheep.

Grievious sins, although committed by Catholics at times, are not part of Catholic teaching and practice, so discounting the Catholic faith because someone sins is like judging the teaching of Christ to be in error because Judas betrayed what he had been taught. It is not logical.