Mortal Sin and the Christian Life

Understanding mortal sin can make the difference between life and death.

This is a critical topic to understand!

This article will tell you what mortal sin is. But this topic is so important, first we'd better look at why you should care deeply about it...

"How important is this?"

Mortal sin makes it impossible to follow Christ.

The very first step in the life of faith is to hear God's call and answer with the response of faith. This is your response of initial conversion.

The second step is to become free of mortal sin.


Because mortal sin is a refusal of God's offer of live and love. It's that simple. No matter how much you want to love God, no matter how strong you feel your budding faith life is...

... a single act of mortal sin is a bold declaration that you do not accept God's love.

Mortal sin destroys charity in the heart of man by a grave violation of God's law; it turns man away from God, who is his ultimate end and his beatitude, by preferring an inferior good to him....

Mortal sin is a radical possibility of human freedom, as is love itself. It results in the loss of charity and the privation of sanctifying grace, that is, of the state of grace. If it is not redeemed by repentance and God's forgiveness, it causes exclusion from Christ's kingdom and the eternal death of hell, for our freedom has the power to make choices for ever, with no turning back.

(Catechism, 1855 & 1861)

That's why it's called mortal sin — mortal means "death."

He who does not love abides in death.

(1 John 3:14)

The topic of mortal sin helps us understand something that isn't widely believed these days: the connection between our faith and our acts.

We prove our faith by our acts

There's a very dangerous idea floating around: the idea that our faith is somehow separate from our actions.

Some people seem to think that they're good Christians even though they're deliberately committing acts that are seriously, objectively wrong. They still believe that their faith life is alive and growing.

That is a false belief!

Pope John Paul II wrote that "The Apostles decisively rejected any separation between the commitment of the heart and the actions which express or prove it...." (Veritatis Splendor, 26)

In fact, it is specifically by walking the path of a moral life that we accept the free gift of salvation and everlasting life. "Coming to see in the faith their new dignity, Christians are called to lead henceforth a life 'worthy of the gospel of Christ.'" (Catechism, 1692)

Since ancient times, the Catholic Church has taught about "the two ways":

The way of Christ "leads to life"; a contrary way "leads to destruction." The Gospel parable of the two ways remains ever present in the catechesis of the Church; it shows the importance of moral decisions for our salvation: "There are two ways, the one of life, the other of death; but between the two, there is a great difference."

(Catechism, 1696)

What this means is that your actions matter!


The doctrine of mortal sin teaches us how to recognize those actions that absolutely destroy the life of faith itself.

So now let's take a closer look...

"So, just what is mortal sin?"

Mortal sin is death to the soul.

"Sin" is a thought or action that is, at root, an offense against God. It's a violation of the great commandment to love God above all else, and to love your neighbor as yourself. (See the main overview of Catholic morality for the big picture.)

Catholic Tradition and Scripture name two categories of sin: mortal sin and venial sin.

  • Mortal sin is serious enough that it kills the life of grace within us.
  • Venial sin is not deadly by itself, but it's still quite dangerous. It offends God, hinders our ability to receive grace, damages our soul, and wounds our ability to live as a Christian.

Mortal sin is that minimum line below which we cannot go.

Every act of mortal sin effectively refuses God's offer of grace and life — with such an act, we choose death.

Three conditions for mortal sin

There are three conditions that make an act a mortal sin:

  1. An act of grave matter that is...
  2. Committed with full knowledge and...
  3. Deliberate consent.

All three conditions must be met for it to be a mortal sin. If one condition is seriously lacking, it's not mortal — it's considered a venial sin. (See the Catechism's section on mortal sin, numbers 1854-1864; opens new window.)

Of course, such actions are still wrong!

A lack of knowledge or freedom only reduces our culpability (our degree of responsibility or guilt). We've still committed an act that is objectively evil. Such an act cannot help us to grow in grace, virtue or charity. The only upside is that our reduced responsibility means that we don't kill the life of grace entirely.

Obviously, it's important to understand these conditions!


Grave matter

The term grave matter means a serious act contrary to the moral law.

The Ten Commandments are the standard reference point for defining grave matter.

  • Remember that each commandment is really a category, though. Don't think you're off the hook because technically you didn't "worship a false idol", for example!
  • A good Catholic Examination of Conscience will help you sort out the kinds of things considered to be grave matter.

I should clarify two important things here.

First, a serious act is required. Telling your mother you forgot to put your shoes away (when you didn't), is not the same as perjury or tax fraud. Minor violations are usually seen as venial sins unless serious harm results, or they are committed with real malice. (See Catechism, 2484)

Second, don't look at that point about serious acts and try to use it as a loophole! The term "act" also includes deliberate thoughts. As Christ himself said, "I say to you that every one who looks at a woman lustfully has already committed adultery with her in his heart." (Matt 5:28) We take that seriously.

Full knowledge

For an act to be a mortal sin, we have to have full knowledge of its sinfulness. We have to know:

  • That it is wrong; and
  • That we are committing the act.

Much of the time, we know what acts are gravely wrong. Because of something called the "natural law", we have a natural understanding of the universal norms of morality.

We don't always recognize the natural law clearly because sin clouds our vision of it. So...

We also have the obligation to form our conscience, so that it can judge accurately and bear witness to the objective moral truth.

We can't get off the hook here by just pretending ignorance, or by willfully remaining ignorant to justify some behavior. This actually increases our culpability! It's also no excuse if we fail to make the effort to form our conscience based on divine law as revealed in Scripture and Church teaching. (See Catechism, 1859-60, and also 1783-5, 1792, 2039)

But there are situations where someone honestly does not know that an action is wrong. They're ignorant of the law, and they couldn't reasonably have learned the truth. In such cases the person is not guilty of mortal sin.

Likewise, it's not a mortal sin if you don't know you're committing the act. For example, if you pick up a bag of money that you believe to be your own, it's not theft if it turns out to be someone else's.

Deliberate consent of the will

Mortal sin also requires deliberate consent. This means that you make a free choice to commit the act.

The state of freedom is something that defines us as human beings. Freedom is the ability to choose to act or not to act. With freedom comes the responsibility for our choices. (See Catechism, 1731)

Sometimes, there is some factor that seriously interferes with our ability to make a free choice. These cases reduce our culpability for sin. Perhaps some factor slightly reduces the malice of our action. Other times, if we're seriously unfree, it may reduce the gravity of our responsibility for the sin, making it a venial sin. (See Catechism, 1735, 1860, 1862)

Honestly, this is the hardest factor to determine accurately. At times we know clearly that our choices are indeed deliberate. In other cases, we're honestly not sure.

We know that God sees the truth completely and with great clarity. But here on earth, things can be a little cloudy.

Complicating factors can include:

  • Physical force or other strong coercion
  • Great fear or anxiety
  • Extreme fatigue
  • Hidden or deep-seated emotional wounds
  • Long-established habits

It's also the case the that sin tends to pull us into a downward spiral. What begins as a small matter becomes a habit. It dulls our perception of sin. We get used to sin; it doesn't seem so bad. Little by little, we "up the ante" and slide into mortal sin.

You should know two things here.

First, know that God is infinitely merciful. He knows & accounts for your specific weaknesses, emotional scars, and the full complexity of your particular situation. He loves you, and wants the best for you. After all, he died for you — quite specifically, to set you free from the slavery of sin. Don't despair if you're honestly struggling with something.

Second, do honestly struggle!

It is specifically in this struggle that we grow in virtue. Even if you struggle and fall, the Lord will help you grow in grace because you struggled.

"Another fall, and what a fall! Must you give up hope? No. Humble yourself and, through Mary, your Mother, have recourse to the merciful Love of Jesus. A miserere, and lift up your heart! And now begin again."

(St. Josemaria, The Way, #711)

Seek direction

It's important to know that everyone has some dominant defect that they struggle with. And for many of us, it's more than just one thing!

You should actively seek two things to help you:

  • Healing
  • Guidance

The place for healing is in the Sacraments of Confession and the Eucharist.

Christ established them just for the purpose of healing us and helping us to grow! Nothing else even comes close to these sacraments in importance and effectiveness. (Of course, if you're in a state of mortal sin, you have to go to Confession before you can receive Communion.)

After that, seek guidance in spiritual direction. Many people use Confession as a chance to get informal direction from the priest. That's good, and most priests will be happy to help out.

Even better is to get formal spiritual direction. Ask a priest or trained layperson if you can meet with them periodically for direction. Just make sure you understand the importance of orthodox Catholic opinion when choosing someone. You're placing your life in their hands!

Seek holiness!

Direction is certainly useful for helping to sort out the question of mortal sin in your own life. But more than that... will help you focus your efforts and grow in the spiritual life!

After all, the real goal is achieving holiness! Becoming free of mortal sin is merely the first step in a life dedicated to Christ.

"You, therefore, must be perfect, as your heavenly Father is perfect."

(Mt 5:48)

Read the main article about Catholic morality, or check our home page for other articles about the Catholic faith!