When someone commits a personal sin, he: (1) fails to love God; (2) turns away from pursuing his lifetime goal of doing the will of God; and (3) by means of a serious offense (mortal sin), ruptures his relationship with the Father, the Son, and the Holy Spirit.
To sin is to refuse to let God have His way in our life. We turn away from God because we want to live without regard for His will. When we sin, we choose whatever we think will make us happy, even though it does not fit into God’s plan for our eternal happiness. We fail to trust God completely when we sin. Serious sin makes us unhappy and sometimes even enslaves us to sin. Jesus said, “Truly, truly, I say to you, every one who commits sin is a slave to sin” (John 8:34).