Mortal sins are serious offenses in Christian theology that lead to a complete separation from God's grace. They are considered grave violations of God's commandments and require full knowledge and deliberate consent from the individual committing them. Examples of mortal sins include actions like murder, adultery, and theft. To be forgiven for a mortal sin, a person must genuinely repent and seek reconciliation, often through the sacrament of confession. Unlike venial sins, which are less severe and do not break one's relationship with God, mortal sins can jeopardize a person's eternal soul if not addressed.