Jesus replied. "No one is good except God alone.": This response has troubled interpreters for centuries. Jesus was likely correcting the man’s casual use of the word good for a human being. Perfect goodness belongs to God alone.
Jesus was not denying his own goodness. Instead, he wanted to direct the man’s attention to God. The rich man wanted to enter the kingdom of God, and Jesus contrasted God’s goodness with the man’s own sinfulness.