What does Luke 17:25 mean?

Jesus has explained that the Pharisees misunderstand what the arrival of the kingdom of God means (Luke 17:20–21). To be sure, when God's kingdom is fulfilled, the Son of Man (Daniel 7:13–14) will arrive illuminated by lightning (Matthew 24:29). No one will have to seek out the Messiah; He will be obvious (Luke 17:23–24). But the kingdom of God has already been inaugurated with the incarnation of God the Son who teaches, heals, and casts out demons (Luke 17:21).

Even more unexpectedly, to the Pharisees, the Son of Man first must die. "This generation" includes Jewish religious leaders who reject Him as their Messiah. They're jealous of His popularity with the people (Mark 15:10). They are insulted that He not only rejects their extra-biblical law, but He even condemns it (Luke 11:42–46). And they're afraid of the Romans who will persecute them if they can't keep His followers under control (John 11:47–50).

This isn't the first time Jesus has told His disciples about His coming rejection. Earlier, He warned, "The Son of Man must suffer many things and be rejected by the elders and chief priests and scribes, and be killed, and on the third day be raised" (Luke 9:22). He mentioned it again, but the disciples didn't understand because the meaning was hidden from them (Luke 9:44–45). And He will tell them one more time (Luke 18:31–34).

In this regard, the disciples are only marginally more mature than the Pharisees. They fight over who is greatest among them (Luke 9:46), jockeying for position (Mark 10:35–37). Then they ask to know when Jesus will "restore the kingdom to Israel" (Acts 1:6).

Jesus promises it will come. His return will be sudden, obvious, and a total surprise (Luke 17:24, 26–30). And yet, those who are watching will be able to interpret the signs (Luke 17:37). They need to be ready.