Mark 9:30 (NET) They went out from there and passed through Galilee. But Jesus did not want anyone to know, 31 for he was teaching his disciples and telling them, “The Son of Man will be betrayed into the hands of men. They will kill him, and after three days he will rise.” 32 But they did not understand this statement and were afraid to ask him.
They left secretly
Jesus sometimes spoke to the crowds. Sometimes, to the twelve. At other times, to the three. Some things were meant for those closest to him, those most invested in the mission. This was one of these times. For that reason, he quietly left town with the twelve. He had things to teach them that were for them only.
Difficult times ahead
The time had come for the most difficult part of his purpose to come to fruition. In a short time he would face betrayal, persecution, death and resurrection. That knowledge was only for those closest to him, those assigned to continue his mission after he was taken up.
They did not understand
No matter how often or how carefully he explained it, they did not understand. In their mind, Jesus purpose was to be a conquering king who would save them from Roman oppression, restore Israel and set all things right.
They did not understand his immediate mission was to be the Lamb of God and atone for our sins. Before Israel could be restored, atonement had to happen. Restoration of the people of God is for the future when he returns.
They did not understand and were afraid to ask.