John Calvin writes in his sermon on Galatians 1:6 the following:
In fact, what Paul says here about the Galatians is far too much in evidence today. Those who have been taught the gospel become discontented after three years [or so] if they do not have some novelty or other, for they have ‘itching ears’. Many vain people backside because they are not content with the truth in the gospel. They always want to be moving house [as it were] because they need some new thing to feed their foolish imaginations. Others grow dissatisfied when they see that the gospel has not brought them any of this world’s goods. There are even some who turn away when they find that they may well be persecuted, and have many enemies. Thus, you can see how many desert our LORD Jesus Christ, not just as one generation succeeds another, but even as those who appear to be His followers turn and rebel after three, or perhaps ten years.
The question and battle for all of us: are we satisfied with Christ as He is presented in the gospel? Or do we want more?
Far too many are looking for one spiritual high after another, so that their religion, even couched in the context of Christianity, becomes idolatry. They are not looking to Christ for satisfaction and redemption, but looking to Him for one more miracle, one more fancy trick.
When the Jews came to Him, doing the same thing, Jesus called them “an evil generation.” This is one of those comments that Jesus made that you won’t find on some sappy T-shirt somewhere. They were evil because THE MESSIAH was standing before them, and they wanted fire crackers and cotton candy. Colorful, but quite empty.
The same is true in our generation. There are many people who run around trying to get another sign, another spiritual high, another mountain-top experience, never realizing that Jesus is it. He is the One that should be the center of our focus. Not some experiential moment. Trust in the risen Savior, in His resurrection, and no more. That is the gospel. Adding to it, only changes the gospel into heresy. Which shows us the deeper reality. The more we chase after novelty, the less we are being faithful to the calling God has placed upon us. This is exactly what the Apostle Paul was getting onto the Galatians about. They moved away from Christ, in adding to the gospel.
Paul told those who did so that they were cursed for doing. This was not some sort of backyard curse, but one that meant they had no hope of salvation. In moving away, what are we moving toward? Paul told them clearly: a different gospel, which was no gospel at all. This is the reason he will go on and write “O foolish Galatians.” To tamper with the gospel is utter foolishness.