David defeated the giant Goliath not primarily because he was a good shot with his slingshot or because he was so courageous. David was victorious because he knew that the battle belongs to the Lord (1 Sm 17:47). The all-loving, all-holy, all-knowing, all-powerful God is always victorious. The key to victory is to ride on God's coattails, to jump on His bandwagon, to join God.
David was able to join God in victory because he was a man after God's own heart (see Acts 13:22). Although David sinned very seriously, he repented, and his heart was with the Lord. When our hearts are in His heart and our lives are in His life, that is, when we are in Jesus, we are in love, peace, truth, freedom, and victory.
To be giant-killers after the Lord's own heart, we must repent and decide to deny ourselves (see Lk 9:23) and to live no longer for ourselves but for the Lord (2 Cor 5:15). When we lose our lives and hearts, paradoxically we find them and victory in Jesus (see Lk 9:24).
We are surrounded by giants of abortion, racism, Chinese Communism, starvation, AIDS, and injustice. Powerful, famous, rich, and brilliant people cannot kill the giants. Only those whose hearts are in the right place can defeat giants. Is your heart in the Sacred Heart of Jesus?