The first reading at Mass this week is taken from the first letter of John, which could be called a love letter in the truest sense. Today's reading says, "we have come to know and to believe in the love God has for us." The Greek word that John uses here for love (pepisteukamen) is in the perfect tense. That tense is often used to express great theological truths. It refers to something that happened in the past but continues to have present effects.
In this context, it indicates that our believing in the love God has for us didn't just happen in the past, but keeps on affecting our lives every day.
That has lots of meaning, but one thing came to me about it this morning. God doesn't stop loving us when we sin. That doesn't mean we shouldn't care about sin, but that when we do sin we can have confidence in God's mercy.
It's a very human thing to beat ourselves up when we do something wrong or even just make a mistake. But if we sincerely want to follow the Lord, we can repent of the sin and maintain confidence in God's love. In other words, we don't have to identify with the sin as if it defines us and makes us "bad" somehow. The key is repentance. We can separate ourselves from what we did and take it as feedback in order to do better in the future.