Can mortal sins be forgiven?

Yes. Every mortal sin can be forgiven, however serious it was and however many times you've committed it. The Church teaches that there is no offense, however serious, that she cannot forgive (CCC 982). The ordinary way is Confession: you tell a priest your sins with real sorrow, and his absolution restores you to God's friendship.

Is any sin too big for God to forgive?

No. The Catechism says it plainly: "There is no offense, however serious, that the Church cannot forgive." It adds that Christ wants "the gates of forgiveness" to be always open to anyone who turns away from sin (CCC 982).

The people closest to Jesus prove it. Peter denied him three times on the night he was arrested, and afterward Jesus entrusted his sheep to him (John 21:17). Paul hunted down Christians before he became an apostle. The prodigal son wasted everything, and his father ran to meet him (Luke 15:20).

Many people carry one sin they're sure is too much: an abortion, an affair, years of hatred, something done to a child, something that can't be undone. It can be forgiven. Abortion carries a Church penalty (Code of Canon Law, can. 1397 §2), but since 2016 Pope Francis has given every priest the faculty to absolve it (Misericordia et misera, 12), so you can bring it to any confessional. A few very rare sins carry a Church penalty that needs extra steps, but that's the priest's work to sort out, not yours to solve before you come.

How are mortal sins forgiven?

Through the sacrament of Confession. Christ gave it to the Church above all for those who have fallen into serious sin after Baptism (CCC 1446). Confession of grave sins followed by absolution is the only ordinary way back to God and to the Church (CCC 1497).

Here's what it asks of you:

1. Be sorry. Your sorrow doesn't have to be perfect. Sorrow out of fear of punishment, or because you see how ugly the sin was, is enough for a good Confession (CCC 1453).
2. Confess every mortal sin you remember. Name each one by kind and, as best you can, how many times (CCC 1456; Code of Canon Law, can. 988 §1). You don't need a full story. A sentence each is fine.
3. Intend to change. Not a guarantee that you'll never fall again, only that you aren't planning to, and that you'll try with God's help.
4. Receive absolution and do your penance. When the priest says the words of absolution, your sins are forgiven. Fully.

If it's been a long time, that's no obstacle. Start with "It's been about ten years since my last confession," and the priest will help with the rest. Our guide to how to go to confession walks through every step, and going back after years is written for exactly this moment.

What if I can't get to Confession right away?

Tell God you're sorry now. Don't wait for Saturday. If your sorrow comes from love of God, it's called perfect contrition, and it obtains forgiveness even of mortal sins, as long as it includes the firm intention to go to Confession as soon as you can (CCC 1452). We explain the difference in perfect vs imperfect contrition.

Two things still follow. You still confess that sin at your next Confession. And you wait to receive Communion until you've been absolved, except in rare cases where there's a grave reason and no way to confess (CCC 1457). More on that in can you receive Communion in mortal sin.

In danger of death, the Church makes it as easy as possible. Any priest can absolve anyone in danger of death, from any sin, even a priest who normally isn't allowed to hear confessions (Code of Canon Law, can. 976). And if no priest can come, an act of perfect contrition, with the wish to confess if you could, is enough to turn back to God.

What is the "unforgivable sin"?

Jesus said that every sin and blasphemy will be forgiven, except blasphemy against the Holy Spirit (Matthew 12:31). People often fear they've committed it. The Catechism explains what it means: "There are no limits to the mercy of God, but anyone who deliberately refuses to accept his mercy by repenting, rejects the forgiveness of his sins" (CCC 1864).

So the one sin that can't be forgiven is refusing forgiveness, and holding to that refusal to the end. It isn't a particular act you might have stumbled into. If you're reading this because you want God's mercy, you are not refusing it. We go further in what is the unforgivable sin.

What if I keep committing the same mortal sin?

Keep going back. Jesus told Peter to forgive not seven times, but seventy times seven (Matthew 18:22). He doesn't ask more of us than he gives himself.

Falling again doesn't mean your last Confession didn't count, or that your sorrow was fake. Real sorrow includes the intention to change, not a certainty that you never will fall again. Strong habits, especially in sexual sins, can involve real compulsion, which can lessen how responsible you are (CCC 1735). Confess regularly, ask the priest for advice, and consider a counselor or support group alongside the sacrament. Each Confession gives you grace for the next fight.

What if I forgot a mortal sin in Confession?

It was forgiven along with the rest. If you made an honest Confession and a sin slipped your mind, the absolution covered it. You simply mention it at your next Confession: "I forgot to confess this last time." You don't need to rush back the same day, and you don't need to worry about the Communions in between.

This is different from hiding a mortal sin on purpose. If you held something back deliberately, that Confession needs to be made again: tell the priest, confess the sin you hid and that you hid it, and wait to receive Communion until you have. He will help you put it right. Our page on forgetting a sin in Confession walks through it.

After you're forgiven

Believe it. When the priest absolves you, God isn't keeping a copy of the list. You don't need to confess the same forgiven sins again out of fear. If memories of old sins come back, turn them into a short prayer of thanks: "Thank you, Lord, for forgiving me."

Forgiveness doesn't always undo the consequences. If your sin hurt someone, do what you reasonably can to repair the harm: return what was taken, set the record straight about someone you slandered, apologize where it's wise (CCC 1459). The penance the priest gives belongs to that healing too, a first small step in living differently.

If something is weighing on you right now, look up confession times at your parish or one nearby, pick a day this week, and go. The priest will be glad to see you, and so will God.