You've probably wondered, from time to time, why doing certain things that are considered wrong — even when plenty of people say otherwise — leaves you with a feeling inside, often hard to put into words, telling you that it wasn't right. It's disquieting. 

And that voice doesn't go quiet just because time passes, even when the action, thought, or attitude itself seems to fade from memory over the days, months, or years. That's because sin doesn't go away on its own. It's something that gets into our soul (because we let it in) and never leaves unless God specifically and personally intervenes to draw it out of us.

But what is sin? Some people will tell you that it's something forbidden, but that's not a very satisfying answer. It doesn't get to the heart of it. In reality, sin is anything that offends God. It's a bit mysterious, because God is perfect, eternal, and unchanging... and yet we can offend Him. In fact, St. Paul calls sin the "mystery of evil." God doesn't take offense because He's in our power: He's not. It hurts Him because He loves us, and in sin He sees us hurting ourselves and each other. 

Sin is whatever harms me and others; whatever damages my relationship with others, starting with God my Father and with my fellow human beings. Every sin is something negative that enters the world.

Sin is very serious. St. Josemaría wrote in The Way: "Don't forget, my child, that for you on earth there is but one evil, which you must fear and avoid with the grace of God: sin" (no. 386). 

It's so serious, such a tremendous evil, that only God can forgive it. There are DIY tutorials for a lot of things in our lives: how to unclog a drain, parallel park, treat a cold... And for more difficult problems, we call on experts: if the sink doesn't run at all, we call a plumber; if the car breaks down, we take it to a mechanic; if the cold is serious, we see a doctor. Well, God is the best healer. If you want to fix something that's very badly broken, or cure a really serious illness, you have to go to the expert. With sin, that means going to God, asking Him to forgive us in the sacrament of Penance, also called Confession.

We know this because Jesus Himself spoke often about sin and sinners, and He condemned sin unequivocally. But He also spoke constantly about forgiveness. He came to earth to forgive sins. If you had to sum up everything the Gospel teaches in a single word, it would be "conversion." And conversion begins with recognizing ourselves that we are sinners. As Pope Francis put it so beautifully, "Jesus is the face of God's mercy."

Jesus tells many parables about God's forgiveness and about the reality of sin and its effects. The best known are the prodigal son (Lk 15:11-32), the lost sheep (Lk 15:4-7), and the two debtors (Lk 7:36-50). It's worth reading and reflecting on them often, as a way of drawing closer to this endless mystery of God's merciful love.

Every time we go to the sacrament of forgiveness, we experience God's love firsthand. It's not just about repairing a broken relationship or getting back some peace of mind. Forgiveness isn't just an abstract idea; it's something you experience. It changes our lives. 

Sin leads us into a kind of self-denial, a refusal to become what we were created to be. To sin is to shut ourselves in on ourselves, denying our hearts the very thing they're made for: giving ourselves to others, loving. It's simply not true that someone can sin "out of love." Evil, at its core, is selfish. Sin is the loneliness of being locked inside yourself. That's why God's forgiveness means a new creation, an opening onto the infinite. It's God stepping directly into our lives; his life-giving breath on our soul: "And when he had said this, he breathed on them and said to them, 'Receive the Holy Spirit. If you forgive anyone's sins, they are forgiven; if you retain anyone's sins, they are retained'" (Jn 20:19-23).

It's hard to really grasp what happens each time we approach this wonderful sacrament of God's mercy, won for us by Christ's death on the cross.

It's a genuine interior revolution, one God chose to carry out through the Church. That's why we need the priest, God's minister within his Church. Every time I go to this sacrament, I place myself in God's presence and humbly ask forgiveness, not only from Him, but from the Church and from all of humanity, since my failings wound the Church and the whole human family we belong to. Sin is a mystery of evil, as we said before. And all the evil in the world traces back to original sin and to the personal sins of each of us.

To benefit from this source of forgiveness and healing, all God asks of us is sorrow for our sins and a real intention not to sin again — being willing, with God's help, to use every means we can to correct ourselves. Then we go to the priest, contrite, and name the sins we recall, after a sincere examination of conscience, since our last confession. That's what allows the words of absolution ("I absolve you...") to bring about, in our soul, the new creation of grace. A small penance from the priest then helps make up for, or lessen, part of the temporal punishment still owed for our sins.

This wonderful sacrament helps us return to God, and to rediscover the truth about ourselves and about others. Through confession, our soul starts walking again in the truth of its whole marvelous reality and potential, accompanied by the deep peace that comes from knowing that only in God will I find my happiness, both here on earth and forever.

As Pope Francis often told us, "God never tires of forgiving," so let's not tire of turning to forgiveness whenever we have the misfortune of sinning.