What was Jesus doing or saying that was getting this reaction from people?

Well, for one thing He was saying, "If anyone keeps my word he shall never taste death." In other words, He was claiming that those who followed up on the message He presented would not experience the desolation and finality that the ending of a person's existence in this world normally brings. (John 8:52)

There were many among those who heard Him make this claim who - as a result - thought He was out of His mind, off His rocker, crazy.

Did anyone think otherwise? Well, His disciples certainly did. While others were deserting Him in shock at what He was saying He asked His disciples, "Do you also want to go away?" Peter on their behalf replied, "To whom shall we go? You have the words of eternal life." (John 6:67-68)

The disciples, instead of considering Him crazy, decided there really was something in what He was saying that was worth believing in, indeed relying on. They decided His message could impart the life of God in this world of death.

How did they come to this conclusion? Because they believed and knew intuitively that He was the Messiah, the One Anointed to save God's people from the horrible consequences of sin which included death itself. (John 6:69)

There were also those among the ruling classes of Judea who decided He wasn't crazy. What was their reason for concluding that this man who was saying such things wasn't mad?

They said, "These are not the words of one who has a demon. Can a demon open the eyes of the blind?" They had been given a reliable testimony by a man who been born blind that Jesus had opened his eyes. This work of restoring a blind man's sight was enough for them to counter what others were saying and to declare instead that Jesus couldn't be demoned possessed. In other words, He could not be crazy. (John 10:19-21)

And what about Jesus Himself? What did He have to say on this matter of His sanity? Was He convinced He wasn't crazy? Absolutely. He answered their accusations of madness by declaring, "I do not have a demon" or as one contemporary translation puts it, "I'm not crazy." What did Jesus say in support of that claim? He said, "I do not seek My own glory. I honor My Father." (John 8:49-50)

Notice we've got three different reasons that people gave to support their conclusion Jesus wasn't crazy.

The first was from the disciples. They discounted the possibility that His words were those of a crazy man. On what basis did they do that? On the basis that they were convinced He was the Messiah, the Christ. Believing Him to be the Christ they believed what He promised He was also able to perform.

What, though, convinced them that He was the Christ, the Messiah? The disciples had grown up hearing in the synagogue the words of the prophets regarding the Messiah. In the ministry of Jesus they saw works of a miraculous character that, by every indication, were a fulfilment of those words. For example, the prophet Isaiah said, "The people who walked in darkness Have seen a great light; Those who dwelt in the land of the shadow of death, Upon them a light has shined." (Isaiah 9:2) The disciples witnessed this happening as Jesus ministered in Galilee.

Now take the second reason I've given that people gave for concluding Jesus wasn't crazy. It came from those among the ruling classes of Judea. They gave their reason as, "Can a demon open the eyes of the blind?"

They were referring to the miracle Jesus performed in opening the eyes of a man born blind. This was the type of miracle their scriptures prophecied the Messiah - the Anointed One - would perform. The scriptures, for example, prophecied the coming Messiah's mission statement, "The Spirit of the Lord is upon Me, because He has anointed Me To preach the gospel to the poor...to proclaim liberty to the captives and recovery of sight to the blind." (Luke 4:18)

Jesus' work in restoring the blind man's sight pointed to Him as the Messiah, the Christ. This gave them reason to conclude His claims weren't those of a madman but rather of the Christ. If He were the Christ, what He promised He was able also to perform.

Finally we come to Jesus' reason for declaring He was not crazy. He said, "I do not seek My own glory. I honor My Father." He was not out for self-promotion, His ministry was not about self-exaltation. His entire focus in life and ministry was on honoring His Heavenly Father.

This is not the way of madmen. As you read the words of Jesus you find yourself thinking of Heaven and our Heavenly Father. He draws you to Him. This is the work of the Christ. He brings to you reconciliation with your Heavenly Father. You have been estranged from Him. In Jesus you are brought back into a wonderful father-son relationship.