Why were the disciples confused about the Rapture?

Why were the disciples confused about the Rapture?

Dr. John Walvoord: Now, the doctrine of the Rapture—Christ coming for His own—is a very particular doctrine. Scripture predicts that Christ is going to come bodily from heaven; He’s going to cause Christians who have died to be resurrected; living Christians to be instantly changed to rise from the earth and meet the Lord in the air and then go to heaven. Now, Christ introduced this for the very first time in John 14 and the disciples were struggling with the idea He’s going to leave and He said in John 14:3, “If I go and prepare a place for you, I will come again and receive you to myself, that where I am, there ye may be also.” Now, this fell on absolutely deaf ears for the disciples because they were confused about the first and second coming.
Everybody was confused in the Old Testament and the Gospel. They put the first and second coming of Christ together as if it is one event and they thought He was going to fulfill the promises relating to His second coming. And of course, He wasn’t, and now He introduced this additional element. He’s going to come and take them to heaven. This wasn’t their fore view at all. They were looking for a kingdom on earth. And so He introduced the subject here and then later on through Paul He gives us a further exposition of it.