A farmer went out to sow seeds in his field. Some seeds fell on the path and were eaten by birds. Some seeds fell on rocky ground, where the young plants were withered in the shallow soil. Some seeds fell among weedy soil and were choked out by the weeds. Other seeds fell on good soil and produced a crop.
Jesus had told this parable to the crowds and then later explained its meaning to his disciples. The different soils were an analogy of how people respond to God’s word. Some refuse the word and with many people it is not possible for the word to grow in their hearts. But there are a few that will be the good soil — those who will take the word and grow. (Matthew 13:1-23; Mark 4:1-20; Luke 8:4-15)
John 6 shows an example of the different soils in real life. It starts with the pinnacle of excitement as Jesus had fed a massive crowd (probably about 20,000 people) and they all wanted him to be king. But they start to fall away when Jesus gave them a challenge. Sadly, it is only a few that remain to be the good soil.
This passage can be best summarized by Jesus’ statement about himself: “I am the Bread of Life.”
Jesus had fed the crowd the day before and now the people want more. They had tried to make him king and were rejected. Now they have come back to try again.
Jesus responded simply: they came back for the food, but what they need is eternal life. They need to be born from God.
The rabbis had taught the people that God sets his seal on the one who is truth. Jesus told them that God had sent him and had set his seal of truth on him. They did not need to work but to believe.
The Jews asked Jesus to validate his claims with a sign. According to their traditions, they believed that the true Messiah would provide manna for them, greater than even what was given by Moses. Jesus corrected them that the manna came from God, not from Moses. But manna was only temporary. They need the true bread from heaven which will give eternal life.
Jesus is the true bread. All you need to do is to come to him and believe in him for eternal life. He alone can give eternal life.
This would be simple to understand and believe. But Jesus takes the analogy further. He is the bread of life, and you need to eat his flesh and drink his blood. What does that mean?
The Jewish tradition held that the law and the commandments were the bread and wine for a believing Jew. They had achieved true wisdom when they depended totally on their law. Jesus was saying to this devout Jewish audience to stop looking to the law and their traditions for life, and to instead look to him. They will receive eternal life when they totally depend on him.
They understood it but they did not accept it. It was offensive to them. Given the choice between their traditions and Jesus, many of the disciples left Jesus for their traditions.
“Here, then, we are at the parting of the two ways; and, just because it was the hour of decision, did Christ so clearly set forth the highest truths concerning Himself, in opposition to the views which the multitude entertained about the Messiah. The result was yet another and a sorer defection. ‘Upon this many of His disciples went back, and walked no more with Him.’” 
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