John 12:16 “The disciples did not understand these things at first, but when Jesus was glorified, then they remembered that these things had been written about him and had been done to him.”
How many times did this happen to the disciples? Jesus does or says something and then we are told that the disciples did not understand it when it was happening but then later they remembered what had happened and what it meant.
It happened a lot. It’s like a teenager going out on his own for the first time and realizing that his parents were really pretty smart.
There are two categories of this kind of thing. There are the times like the passage listed above where Jesus fulfills something from the Old Testament that was written about him. In this case it was when Jesus rode into Jerusalem on the donkey on Palm Sunday.
This is how the prophet Zechariah had prophesied it would happen:
Rejoice greatly, O daughter of Zion! Shout aloud, O daughter of Jerusalem! Behold, your king is coming to you; righteous and having salvation is he, humble and mounted on a donkey, on a colt, the foal of a donkey. (Zechariah 9:9)
Then there was the time Jesus cleansed the temple in John 2. After it happened the disciples remembered a passage from Psalm 69: “Zeal for your house will consume me.”
The disciples were no Biblical scholars so it is understandable why they would not make connections to the Old Testament right away. The ones who were the Biblical scholars, who should have made the connections, refused to do so because they refused to accept Jesus as the Messiah.
The other category is things that Jesus said that they later remembered.
In Mark 11 we are told that Jesus went up to a fig tree looking for figs but the tree did not have any. So Jesus cursed the fig tree. The next day they passed by the same fig tree and the disciples noticed that the fig tree was completely withered: “And Peter remembered and said to him, ‘Rabbi, look! The fig tree that you cursed has withered.’” (Mark 11:21)
Jesus told Peter that, on the night of his arrest, before the rooster crowed, he would deny Jesus three times. Peter did not understand this at all and insisted that, even if he had to die with Jesus, he would never deny him. Yet Peter did deny Jesus three times, the rooster crowed, “And Peter remembered the saying of Jesus, ‘Before the rooster crows, you will deny me three times.’ And he went out and wept bitterly. (Matthew 26:75)
Jesus’ death and resurrection falls into this category as well. Several times Jesus told them it was going to happen but they did not understand it until later.
Why did God do it that way? Why did he make the disciples so slow to understand? Did they understand anything about Jesus as it was happening?
Peter was not like, “Well, Lord, since you said I am going to deny you, I guess I’m going to deny you.” Instead he was like, “There is no way I would ever deny you.”
When Jesus cursed it the disciples did not say, “Yep, if we come by here again tomorrow this fig tree will be completely withered.” Instead, when they come by the tree the next day they are all surprised that it had withered.
Why did God do it that way? In a sense, the thief on the cross and the Jewish leaders put the disciples to shame. The thief on the cross, after just a few hours of “hanging out” with Jesus understood what Jesus was all about. He said to Jesus, ‘Jesus, remember me when you come into your kingdom.” And Jesus said to him, “Truly, I say to you, today you will be with me in paradise.” (Luke 23:42-43)
The day after Jesus died and was buried, the chief priests and the Pharisees gathered before Pilate and said, “Sir, we remember how that impostor said, while he was still alive, ‘After three days I will rise.’ (Matthew 27:62-63) So Pilate allowed them to post are guard at Jesus’ tomb.
These kind of things help establish the authenticity of Holy Scripture. If the disciples were just making up these stories they would not have put in these unflattering details.
These stories also remind us that we can trust Scripture completely. If the Bible says something is going to happen it will happen.
Jesus will remember us when he comes into his kingdom no matter how sinful we have been.
Whatever anguish or sorrow we experience will not last: [Jesus said] “When a woman is giving birth, she has sorrow because her hour has come, but when she has delivered the baby, she no longer remembers the anguish, for joy that a human being has been born into the world.  So also you have sorrow now, but I will see you again, and your hearts will rejoice, and no one will take your joy from you.” (John 16:21-22)
One thing that made a huge difference for the disciples was the gift of the Holy Spirit. After they received the Holy Spirit on the Day of Pentecost we never again hear about the disciples not understanding things.
We have the same Holy Spirit who guides us. Jesus assures us: “These things I have spoken to you while I am still with you.  But the Helper, the Holy Spirit, whom the Father will send in my name, he will teach you all things and bring to your remembrance all that I have said to you. (John 14:25-26)
And God knows how our minds work because he created them. Sometimes we understand things better when at first we don’t understand them. When we have to work at understanding things or have to learn things the hard way sometimes those are the lessons we remember the best.