Dear Britty,
Sin is an act against God’s will. Some acts offend more seriously than others. According to the Catechism of the Catholic Church # 1855, “Mortal sin destroys charity in the heart of man by a grave violation of God’s law; it turns man away from God…Venial sin allows charity to subsist, even though it offends and wounds it.”
A an act that is venially sinful will remain that. However, if the act changes, the act can become mortally sinful. For example, if one steals a piece of bread from a bread factory, this could be a venial sin. But if one steals a piece of bread from a beggar who needs it in order to live, then such an act is a mortal sin. The act of stealing a piece of bread itself may be the same, but the act of stealing from a poor person who needs the bread for sustenance is differs considerably from stealing from a bakery where it will scarcely be missed.
A person may steal a dollar from his place of employment on a given day. The dollar is not missed. It is a venial sin. But if the person does this weekly, the amount becomes fifty-two dollars within a year and one hundred and two dollars in two years. In ten years it is five hundred and twenty. At this point we have a mortal sin. The sin didn’t change. The act changed.
Fr. Vincent Serpa, O.P.
