Q. 14. What is sin?A. Sin is any want of conformity unto, or transgression of, the law of God.
The Westminster divines remind us that sin entails both acts of omission and acts of commission. Acts of omission are covered in the first clause - "Sin is any want of conformity unto...the law of God." When we fail to do that which we know we ought to do, that which God has commanded us to do, then we have sinned. As James reminds us, "Therefore, to him who knows to do good and does not do it, to him it is sin" (James 4:17). So be sure to listen to your conscience and to implement the good things you think of doing - don't just think about them.
The catechism also addresses sins of commission: "Sin is any...transgression of, the law of God." To rebel against God, to hear what God says and then to do the opposite, is also sin. Hence, the Apostle John reminds us that "sin is lawlessness." Sin is an attempt to act as god; to pretend that we are the lawgiver and the judge; who will rule over me?
During Ordinary Time we confess our sins with the following words: "Most merciful God, we confess that we have sinned against you in thought, word, and deed, by what we have done, and by what we have left undone." Sins of omission and sins of commission.
Thank God that in His grace and mercy He has not abandoned us to our sins of omission and commission but has rescued and delivered us through His Son, Jesus Christ our Lord! He has rescued us and given us His Spirit that we might, by the power of the Spirit, do those things which honor and please Him. So don't be discouraged: confess your sins of omission and commission and then rise up and hear God's word of pardon and forgiveness, giving thanks to His Name.