The purpose of our Creator is for us to do the goodness which He has prepared for us to do. God has prepared us for good works. We were created to come and do good works. Why we exist is for doing good. He has made all the other lower forms of lives to sustain us. He made the animals to be meat for us. He made the plants life for our sustenance. We are being sustained by all the other creatures in the universe. This is because God prepared us to do good.
The goodness of God must be manifested through our lives. We must be doers of good works. We must love others. We must help those who need help. We must cloth those who have no clothings. We must feed those who are hungry. Doing good is the purpose of our existence.
We are not going to live only for ourselves. We are not going to be those who hurt other people. We are not going to those who do not care for the wellbeing of others. We are not going to be harmful. We must be doers of good works. That is the purpose of God for our lives.