Jesus miraculously fed the multitude at Tiberias. Later, in Capernaum, Jesus said to the disciples who came to Him, "'Truly, truly, I say to you, you seek Me, not because you saw signs, but because you ate of the loaves and were filled.'"
The disciples saw that what Jesus did was a "wonder," but they did not see the miracle as a "sign." The miracle was a sign that Jesus was divine. As the divine Son of God, He could feed their souls as well as their bodies. Obviously, they were more interested in their bodies.
Today many people are searching for God. Unfortunately, like the disciples of old, many are interested mainly in a god who will give them food for their bodies. Some go beyond physical needs and seek for spiritual blessing, but their search is misplaced. Millions of people seek God, but they do not see Jesus as the Son of God.
One, do not work for food that perishes.
Many people, in the time of Christ, sought for free food. As Keener explains, "Roman emperors and other politicians kept the Roman people pacified with free food. Like Roman clients, the crowds join Jesus' 'entourage' just for 'a handout of food'; clients in return ought to advance their patron's political ambitions."
Jesus exhorted the disciples not to search for the food that perishes. Clearly, the disciples, like all men, had to eat. What Jesus means is that food for the body is not the highest priority. They are not to live, as Jesus elsewhere (Matthew 4:4) says, "on bread alone."
Two, the disciples should seek after the food which endures to eternal life.
Jesus is giving his "bread of life discourse." Jesus is the bread of life. Those who eat His flesh and drink His blood will have everlasting life. To eat His flesh and drink His blood is to believe in Him and to identify with Him.
This is the crux of the matter! All who seek God must know that the way to God is through Jesus Christ. He is the only One who could atone for our sins. He is the only One who can redeem us and transform us. The Son of Man is the One who gives us eternal life.
Three, we can have full confidence in Christ because God has set His seal upon Him.
When and how did God do this? A high point was when the Spirit descended upon Jesus at His baptism. A voice from heaven declared (Luke 3:22), "'Thou art My beloved Son, in Thee I am well-pleased." Also, God sealed Jesus through the miracles that Jesus performed.
By setting His seal upon Christ, God endorses Him. The key is that God makes it plain that Jesus is divine. Our proper response is to believe fully in Christ and be faithful to Him.
Four, through our testimony we must seal Christ as well.
John 3:33 says, "For He whom God has received His witness has set his seal to this, that God is true." God seals Christ, but in a lesser way, we seal Him too. We do this through our acceptance of Christ and our testimony. Our testimony is a powerful witness to those who seek salvation.
Those who follow God fully live a Christ-centered life. The reason is very simple. God has set His seal upon Christ as the Redeemer of the world. We are not in the dark about whom to follow. It is through Christ that we have salvation. Our response is to seek after the food that leads to eternal life, to testify of the grace of God, and to witness to others.