When we have a changed of mind, realizing a need to confess sin, then our actions and attitudes will prove it.
Those who "say" they are sorry for their sin, but keep on doing it, are lying. Sorrow over sin brings changed actions and attitudes.
James 2:18-24 "18 But someone will say, “You have faith, and I have works.” Show me your faith without your works, and I will show you my faith by my works.
19 You believe that there is one God. You do well. Even the demons believe—and tremble!
20 But do you want to know, O foolish man, that faith without works is dead?
21 Was not Abraham our father justified by works when he offered Isaac his son on the altar?
22 Do you see that faith was working together with his works, and by works faith was made perfect? 23 And the Scripture was fulfilled which says, “Abraham believed God, and it was accounted to him for righteousness.” And he was called the friend of God.
24 You see then that a man is justified by works, and not by faith only."