There are thieves who are not tempted by petty cash and who will remain models of honesty in the world as long as they are not tempted by a real haul.
In other words, it is not at all a simple matter of outer actions.
There can be a devout scholar who is inwardly just as wicked as any, but because he has no other strong impulse but the intellectual urge, he will be considered a saint.
And yet he can never correct anything in himself because he has never gained any knowledge of his evil potential.
–Rabbi Adin Steinsaltz
From "The Wicked Man Who Pospers," in The Long Shorter Way by Rabbi Adin Steinsaltz