In a great mountain top experience Jesus and three of His disciples had on the Mount, came down, and found a man with a demon possessed son had asked the other disciples of Jesus to deliver the child. They could not. Jesus did.
Now they are going through Galilee, and Jesus is teaching them, reminding them of a perilous time ahead. It was in motion. It was going to happen. Nothing could stop it.
“And they departed thence, and passed through Galilee; and He would not that any man should know it. For He taught His disciples, and said unto them, ‘The Son of Man is delivered into the hands of men, and they shall kill Him; and after that He is killed, He shall rise the third day.’ But they understood not that saying, and were afraid to ask Him. Mark 9:30-32 (KJB)
We can see what Jesus means. We have twenty twenty vision; because it has happened just as He said. Let us not judge the disciples too harshly. They loved Jesus and could not stand the thought of His death, because they did not understand that that is why He came. They were still of the mindset that He was going to overthrow the Romans, and be King of the Jews at that time. Jesus was reminding them otherwise.
As Christians in 2019 we need to remember that this same Jesus who died on the cross, was buried, and rose again just as He said; that He will come again, take those who are His unto Himself, and will, after much tribulation set up His kingdom on earth.
Believe Him. Call on His name.