A Piling of Sin
Sandra Lavin, writing about coming to grips with having an abortion, makes an important point:
If I had to say why I had an abortion it would all begin with the decision to begin that illicit relationship and then all of the nets of sin that suffocate you without you even knowing it. One sin leads to another leads to another until you no longer even recognize yourself. Your conscience is deadened.
One can withdraw the religious terminology without losing the essential insight. Sin requires compounding sin, all mutually reinforcing each other. One could also say that error, self-deception, or whatever, does the same.
The consequence also translates into both religious and secular terms: The more one invests in a particular sin, error, or self-deception, the more difficult it becomes to reassess. In the case of abortion, the weight upon a woman’s decision to kill her own child must be terrifying, giving her huge incentive to push doubts away. Similarly, those who’ve assisted or even generally supported the broad legality of abortion can’t but see the possibility that they’re wrong as the possibility of a monumental indictment.