Sins of omission: the good we fail to do

A sin of omission is failing to do a good you knew you should do, when you could have done it. It's the second half of the line Catholics pray at Mass: "in what I have done and in what I have failed to do." Most sins of omission are venial, but some are grave, like deliberately skipping Sunday Mass or seriously neglecting your family. You confess them like any other sin: say plainly what you left undone, and roughly how often.

What is a sin of omission?

The Church sorts sins in several ways. One of them is "in thought, word, deed, or omission" (CCC 1853). A sin of commission is something you do: a lie, a theft, a cruel word. A sin of omission is something you leave undone: the help you didn't give, the apology you never made, the prayer you skipped because you didn't feel like it.

Two things make an omission a sin. There was a real duty or a clear call to do good, and you knew it and could have acted, but chose not to. Forgetting in good faith isn't a sin. Neither is being unable. And no one is obliged to do every good thing in the world. You can't help everyone who is struggling. You can help the person God puts in front of you.

What does the Bible say about sins of omission?

The clearest line is in the Letter of James: "Whoever knows what is right to do and fails to do it, for him it is sin" (James 4:17).

Jesus makes the same point, more strongly, in his picture of the Last Judgment (Matthew 25:31–46). The people on his left aren't accused of crimes. They're told that he was hungry, thirsty, a stranger, naked, sick and in prison, and they did nothing. When they ask when they ever saw him in need, he answers: "as you did it not to one of the least of these, you did it not to me" (Matthew 25:45).

Two more stories teach the same thing. In the parable of the Good Samaritan, a priest and a Levite see the wounded man and pass by on the other side (Luke 10:31–32). And the rich man in Luke 16 is never described hurting Lazarus. He simply ignored the poor man lying at his gate.

Why the Confiteor mentions what we failed to do

At the start of Mass, the congregation often prays the Confiteor: "I confess to almighty God and to you, my brothers and sisters, that I have greatly sinned, in my thoughts and in my words, in what I have done and in what I have failed to do." The Latin is shorter: opere et omissione, in deed and in omission.

It's easy to say those words every Sunday without noticing them. They're a weekly reminder that a good conscience isn't only about avoiding wrong. It's also about the love you were asked to give and didn't.

Examples of sins of omission

Most of these are small, everyday failures. A few can be serious, depending on the duty involved and how much you knew and chose.

• Toward God: going weeks without praying at all; missing Sunday Mass without a serious reason; staying away from Confession for years while aware of serious sin.
• Toward your family: not providing for your spouse or children when you could; never teaching your kids the faith; refusing to apologize; ignoring an aging parent who needs you.
• Toward others: not helping someone in real need when you easily could; staying silent while someone is slandered in front of you; not paying back what you owe; not returning what you borrowed.
• At work and school: not doing the work you're paid for; letting a colleague take blame you know belongs to you; not reporting something serious when it's your job to report it.

The Church also counts not stopping someone else's sin, "when we have an obligation to do so," as a way of sharing in it (CCC 1868). A parent who sees a child heading somewhere dangerous and says nothing is one example.

When is a sin of omission a mortal sin?

The same three conditions apply as for any sin: grave matter, full knowledge and deliberate consent (CCC 1857). If one is missing, the sin is venial. You can read more about each condition in what is a mortal sin.

Omissions that can be grave include:

• Missing Sunday Mass or a holy day of obligation on purpose, without a serious reason like illness or caring for a baby. "Those who deliberately fail in this obligation commit a grave sin" (CCC 2181). More in is missing Mass a mortal sin.
• Seriously neglecting your family, such as leaving your children without support, care or protection you could give.
• Refusing to help someone in grave danger when you could do it without serious risk to yourself.
• Deliberately leaving a mortal sin out of Confession. Hiding it on purpose makes the Confession invalid. Forgetting one honestly is different: you're forgiven, and you mention it next time.

Most daily omissions are venial: the morning prayer you skipped, the call you kept putting off, the kind word you held back. They still matter. Small omissions, repeated, can harden into indifference.

How do I confess a sin of omission?

Say what you didn't do, as simply as you'd say what you did. For example:

• "I missed Sunday Mass twice without a good reason."
• "I haven't prayed at all for about a month."
• "I've neglected my mother. I haven't called or visited her in months."
• "I let a coworker be blamed for my mistake and didn't say anything."

For mortal sins, give the kind and roughly how many times. For venial ones, it's good to confess them, but you don't have to list each one. When you examine your conscience, add a second question to the usual one. After "What did I do wrong?" ask "What good did I leave undone?"

Don't let it turn into worry

Thinking about omissions can make some people anxious, because there's always more good you could have done. That isn't what the Church asks. God asks you to be faithful to the duties of your own life and open to the needs he puts in front of you. He doesn't ask you to carry the whole world. If you find yourself worrying about every possible good you missed, read our page on scrupulosity and talk to your confessor.

A good place to start is small. Think of one thing you've been putting off: a call, an apology, a visit, a prayer. Do it tomorrow.