In The Brothers Karamozov, the Grand Inquisitor asserts a humanistic critique of Jesus' teaching as the devil did in "The Temptation of Jesus" in Luke 4.
First, here's what Jesus said:
1. Man does not live on bread alone.
2. Worship the Lord your God and serve him only.
3. Do no put the Lord your God to the test.
For the most part, The Grand Inquisitor says the Church has had to undue all of Jesus' mistakes since he died. (Dostoevsky really demonizes the Catholic church here, equating it with Satan's arguments). Wheres Jesus' death condemned man to be free, the Church has had to foster community through security: charity, brotherhood, and service.
The Grand Inquisitor takes "bread" to mean a kind of "free will." He thinks that there are two types of humans since Jesus has died:
1. Those with free will: those who can handle freedom. He estimates these to be the tens of thousands. Less than one- hundredth of one percent.
2. Those without free will: those who can't handle freedom. He estimates these to be the thousands of millions. The other 99.99%
Therefore, since most humans are incapable of handling freedom, the church--or some institution--must provide support and give direction to their empty, wayward lives.
The Grand Inquisitor says "man was created a rebel; and how can rebels be happy?" As such, he rejects Jesus' teachings on simple love and forgiveness as a guiding philosophy.
The Grand Inquisitor rejects Christ because he set the bar too high. He rejects the idea that one can become like Christ: that one man alone can change the world. He says, "What is essential is that all may be together in it. This craving for community of worship is the chief misery of every man individually."
The Grand Inquisitor rejects Christ as the Savior. He says the Christ-as-individual only brings suffering: "Nothing is more seductive for man than his freedom of conscience, but nothing is a greater cause of suffering."
So, overall, the Grand Inquisitor rejects the individual, rebellious, and suffering Christ. Rather, he champions the communal, acquiescence, and prosperity.