"In little more than a year you who feel secure will tremble; the grape harvest will fail, and the harvest of fruit will not come. Tremble, you complacent women; shudder, you daughters who feel secure! Strip off your fine clothes and wrap yourselves in rags. Beat your breasts for the pleasant fields, for the fruitful vines and for the land of my people, a land overgrown with thorns and briers - yes, mourn for all houses of merriment and for this city of revelry. The fortress will be abandoned, the noisy city deserted; citadel and watchtower will become a wasteland forever, the delight of donkeys, a pasture for flocks," NIV translation
This passage describes the period of time that is commonly called the Great Tribulation which is a time when God removes His hand of provision from the world. We see that the purpose is to get the Jewish people to repent and accept the fact that their entire religious system pointed to the first coming of Jesus Christ. We also see that the reason that they continue to hold onto their religion is pride as God urges them to exchange their fine clothes for rags.
Many people (both Jew and Gentile) are proud of their religion and obedience to a set of rules. The fact that they are still on the earth (while most Christians have been removed) and they are going through this terrible period of time is meant to wake them up.