Question for Jehovah's Witnesses in particular, and members of other religions?

Jesus said: He come to the world for the sinners not for the righteous people.If a person is trully repeantant for his sin and change his bad ways we should not hold that agains the person.We are selves are sinners and we should not look others that we are holier than we are.If God can forgive us,why can't we?