Question: Is gossip a mortal sin?
Answer: To really ask this question, we must consider the Eighth Commandment: “You shall not bear false witness.”
In its reflections on this commandment, The Catechism of the Catholic Church invites us to not only think about what bearing “false witness” means, but to also consider how we understand the truth and how we communicate more broadly. This is why so much of this section of the Catechism has to do with the gift of language. With this in mind, we will notice that the word “gossip” isn’t used by the Catechism. Instead, we find the words “detraction” and “calumny,” which are actually two forms that gossip can take, and both can be quite serious.
First, detraction is the of revealing “another’s faults and failings to persons who did not know them,” without morally valid reasons. Calumny, by extension, is saying something about another person that is untrue, and it is sinful because it “harms the reputation of others and gives occasion for false judgements” (see no. 2477).
In all of our communication, we have to always recognize that we have a moral obligation to the truth and to always work to protect the reputation and honor of our neighbors (see no. 2479).
Gossip can, in fact, prove to be a very serious sin. After all, the Catechism reminds us: “No one is bound to reveal the truth to someone who does not have the right to know it” (no. 2489). When we have gossiped, especially if we are aware we have damaged another person’s good name or reputation, we want to make every effort to undo the damage we have done, including seeking the grace and forgiveness offered in the Sacrament of Reconciliation.