The key to remember is that the abomination of desolation causes the Great Tribulation. The language doesn’t allow any separation in the events of v.15 and v.21. It stands to reason that Titus’s actions, at least on this reading, cause the Great Tribulation. Moreover, and Matthew Henry is very clear on this, the Great Tribulation is cut short only by the return of Christ. Therefore, any tribulation you experience today as a Christian is ultimately caused by Titus’s actions in AD 70. This is the practical conclusion historicists not only must draw, but in fact do draw.
verse 15: The Romans setting up the abomination of desolation in the holy place.
verse 21: links it with the Roman armies, which makes sense.
The tribulation of those days includes not only the destruction of Jerusalem, but all the other tribulations which the church must pass through; not only its share in the calamities of the nations, but the tribulations peculiar to itself; while the nations are torn with wars, and the church with schisms, delusions, and persecutions, we cannot say that the tribulation of those days is over; the whole state of the church on earth is militant, we must count upon that; but when the church’s tribulation is over, her warfare accomplished, and what is behind of the sufferings of Christ filled up, then look for the end.
verse 15: From signs, Christ proceeds to the immediate cause of the destruction of Jerusalem; which was, “the abomination of desolation.”
verse 21: The burning of Sodom and Gomorrha, the bondage of the children of Israel in Egypt, their captivity in Babylon, and all their distresses and afflictions in the times of the Maccabees, are nothing to be compared with the calamities which befell the Jews in the siege and destruction of Jerusalem.
Unlike Henry, Gill seems to limit the entire discussion to AD 70 on this point. He doesn’t draw the conclusion Henry does.