"Wherefore I say unto thee, Her sins, which are many, are forgiven; for she loved much: but to whom little is forgiven, the same loveth little." (Luke 7:47 KJV) .
God forgives our sins. It doesn't matter how small or big we think our sins are. The truth is every unrighteousness is sin. Every disobedience to God is a sin. When we confess our sin to God, He forgives us. Confession and repentance are the two conditions for forgiveness. Forgiveness is not automatic. No matter how small or big your sin may be, don't let it ruin your relationship with God. He loves you, and He cares for you. Confess your sins to Him, and repent, He will forgive you.
In our text, we see a woman who had "much" sin, and a man who had "little" sin. The woman had seven demons in her and she was also the town prostitute. She was notorious for her evil deed, and Jesus saved her and cleansed her. When she had an opportunity to show appreciation to Jesus, she couldn't show enough appreciation.
The other man was Simon, he wasn't demon possessed or anything, but he was still a sinner and Jesus saved him and cleansed him. But he couldn't understand why the woman was making such a big show of her gratitude to Jesus!
But gratitude is a question of how we feel, and don't let anyone talk you down for feeling grateful. If you feel the need to show big gratitude, do so. Your heavenly father understands.