St. Paul speak of the example of the Church in Macedonia and their generosity in giving help to the Church in Jerusalem, while the Corinthians did nothing to help Jerusalem. The Christians in Jerusalem were in a great persecutionand needed monetary help to survive. This is the beginning of the awareness that the Church is universal and we are all brothers and sisters together. St. Paul would need help those three years he was under house arrest in Rome and some communities would send help. He calls the Corinthians to be generous in all aspects of their lives.
In the Gospel, in the most radical section of the sermon on the mount Jesus tells us we're not to love only our countryman nor hate our enemies, but we are called to even love those who hate us, those who try to do us harm. Why? because he forgave those who put him to death on the cross. As Christians we are called to follow His example in every aspect of our lives. It is easy to say I love my neighbour, but it is hard to say we love our enemy.