This is a scriptue that Christian disciples and evangelists should hold dearly. We must always remember that God has built in to each person an understanding of good, and that all cultures have survived (almost instinctively) on being good to others who are good to us. But doing good to those who hate us - that is what still wins 99% of people to the gospel even today. Field research and interviews with secular people has proven this - people need time and a consistent display of grace demonstrated to them to come to Christ. After all, is that not how we came to His mercy? Think about your conversion experience...and you will know it's true.