The Church teaches us many things that can help us understand suffering. First of all, human beings are "subject to ignorance, suffering and the dominion of death, and inclined to sin" only as a result of the Original Sin committed by Adam and Eve (see paragraph 405 of the
Catechism of the Catholic Church). Think about this for a minute. An awful lot of the suffering we go through is the direct result of a bad choice that someone (whether we ourselves or someone else) made.
Another thing to keep in mind is that "evil" is more accurately understood as a "lack of good" than as anything in and of itself. In other words, even when we talk about Satan, a fallen angel who tempts people to sin, as in paragraph 391 of the
Catechism, we always affirm that God is far more powerful than the devil and will win the ultimate victory in the end.
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