Can anyone tell me the history behind 2 Corinthians 15?

This was during the 500 year period of Israel's history known as the Apostacy. They worshiped idols. The true believers in God were to be spared (the mark). The idolators who refused to turn from their ways faced God's judgment at the hands of the ruthless Babylonian conquerers who slaughtered them. This is what is meant by these passages.