'Sin' in the Bible

For this reason I say unto you, Every sin and injurious speaking shall be forgiven to men, but speaking injuriously of the Spirit shall not be forgiven to men.

But if thy brother sin against thee, go, reprove him between thee and him alone. If he hear thee, thou hast gained thy brother.

Then Peter came to him and said, Lord, how often shall my brother sin against me and I forgive him? until seven times?