Mat 24:15 When you therefore shall see the abomination of desolation, spoken of by Daniel the prophet, stand in the holy place, (who reads, let him understand:)

Alternative: Therefore, when you see something disgusting that appalls you, as Daniel the prophet said, stood up in a holy place, recognize what you are seeing.

This continues the idea of the earlier parts of this chapter that those people who trust in universal rules cannot be victims of the latest fashion. We see this in our own time. Acts that have been considered completely worthless and corrupting for most of history are suddenly considered not only respectable but holy. Gay marriage is an obvious example, but the idea is more universal than that.

Christ is saying that those who follow the crowd and those are constantly looking for the a new saviors are willing to embrace anything, no matter how disgusting. What was once considered disgusting is suddenly not only acceptable but quite fashionable.

In Daniel, this complete loss of common sense, where good and bad reverse themselves, is seen as a sign that the current age is coming to an end, that civilization cannot continue along its present course. Daniel (Dan 12:11) says that this leads to the "end of days," or, as the Apostles asked in the beginning of this chapter, to the end of an era: the fall of Rome, for example.

So we have Christ bringing in the second ideas of "end" here. In the sense of "end" as the goal or purpose of his teaching, Christ says that his message will allow people to survive. This purpose is necessary because human civilization always rises and falls. He wants to protect people from the "fall," which is the other sense of "end," the end of an era.

"Abomination" is from bdelugma , which means "abomination," but this word appears only in the NT. A related word, bdelugmia, means "sickness," "nausea," "filth," and "nastiness." The verb form, bdelussomai, means "to feel loathing for food," "to make stink," and "to make loathsome." The most common word of this base is the adjective, bdeluros, which means "disgusting" and "loathsome."

In the source reference, Dan 12:11, the Hebrew word is shiqquwts, which means "destable things," "idol," "impure clothing," and "flesh of victims." The root, shaqats, means "to contaminate," and "to pollute."

"Desolation" is erêmôsis, which means "making desolate." It is from erêmoô, which means "to strip bare," "desolate," "to lay waste," "to abandon," "to desert" "to bereave," and "to be left without."

The Hebrew source is shamem, which means "to be desolate," "to stun," "to be appalled," "to devostate," "to ravage," "to cause horror," and "to cause oneself ruin."

"Who reads" is from anagignôskô, which means "to know well," "to know certainly," "to recognize," "to attend lectures," and "to read aloud."

"Understand" is from noeô, which means "to observe," "to perceive by the eyes," "to perceive by the mind," "to think," "to reflect," "to think out," "to devise," and "to intend."