We read yesterday about Antiochus IV's persecution of observant Jews. As we see in today's passage, that persecution intensified to the point of mass executions and defiling the temple with pigs. The "desolating sacrilege" the author mentions probably refers to a statue of Zeus, who was proclaimed to be the god of all. The same phrase shows up in Mark's Gospel when Jesus describes the coming end of the world. Even in the darkest hour, God is still present.