Sin is so bad that when Adam and Eve sinned, human nature became wounded and fallen from that moment till the end of the world.
Sin is so bad that the Israelites were punished with forty years of wandering in a desert because they sinned by refusing to enter the promised land (Nm 14:34).
Sin is so bad that 70,000 people died in a three-day pestilence because of one of David's sins (2 Sm 24:15).
Sin is so bad that millions of innocent people, even children, suffer terribly because of the sins of others (see Mt 15:22).
Sin is so bad that we brutally tortured, crucified, and murdered Jesus by our sins.
Sin is the worst of all evils and the cause of all evils. There would be no way to be freed from sin but for the blood of Jesus shed for us on Calvary.
Therefore, repent of sins, go to Confession, and encourage others to do the same.