There is no gap between verse 23 and verse 24. In fact, in verse 24 the word ‘cometh’ is in italics, which means it is not in the Greek.
That is a very important ‘then’; it means ‘at that time’. Some people try to stretch the word ‘then’. ‘Oh no,’ they say, ‘it doesn't mean then and there; it means afterwards, over a period of time, at some subsequent time.’ ‘No,’ says the apostle, ‘at Christ's coming, then, immediately at that time, ‘cometh the end.’ It cannot mean anything else the way in which it is put in the Greek. ‘But Paul, you’ve forgotten something. What about the millennium?’ Well it's a fact: Paul has never heard of the millennium. Search all the epistles of Paul; he had never heard of the millennium. Search all the words of Christ; he too had never heard of it, and he is the eternal Son of God. So how can there be a millennium? It is in the Book of Revelation, but it must be a figure, not a literal thousand years, because no one else knows about it in the New Testament.
There is a point of view quite popular with many Christians, that Christ has two comings, and that there are even two resurrections: the teaching of the New Testament on this subject is turned into a complicated series of events. The Scripture is much simpler than that. There is only one resurrection. We can show this by looking at a few verses. In John 6 Christ says over and over again that the saints will be raised right at the end of history, at the last day (verses 37, 40, 44, 54). There is only one return of Christ, and only one resurrection of both they that have done good, and they that have done evil at the same hour (John 5:28-29). It will all take place at the same time, on the last day. Matthew 24:30 tells us of the coming of the Son of man in the clouds of heaven to gather his elect, and at the same time to all who do not believe, will mourn. That same coming at that same time will produce mourning and fear in the lost and great blessedness in the elect. The apostle Paul teaches exactly the same (2 Thessalonians 1:7-8).