In today's Gospel reading from Luke 6, Jesus said, "Why look at the speck in your brother's eyes when you miss the plank in your own? How can you say to your brother, 'Brother, let me remove the speck from your eye,' yet fail yourself to see the plank lodged in your own? Hypocrite, remove the plank from your own eye first; then you will see clearly enough to remove the speck from your brother's eye."
The reason we don't have a peaceful world is because everybody is constantly criticizing everybody else. What Jesus has given us is really a formula for peace. If we all examine ourselves first and realize how imperfect we are, we probably won't think ill of others much anymore. Besides, looking inward helps us in keeping in touch with God.