In today's reading from Matthew 18 at Mass, Jesus used a parable to teach Peter to keep forgiving a brother who has sinned against him. The lesson is that we should forgive others as God forgives us. In essence, always treat others the way we expect God to treat us. The ultimate goal is then to save all souls by loving them because God loves us all. Mark 8.35, Jesus saying "Whoever loses his life for my sake and for the sake of the gospel will save it" ties in well.