Why did the age of grace end, and what came after it?
The age of grace ended with the outcalling of the Church before the tribulation began. After it came the tribulation, during which the wrath of the Lamb is poured out; the text even asks who shall be able to stand.
Les teaches that while God is a God of grace tonight and is not pouring out His wrath, grace has now ended. It ended with the outcalling of the Church before the tribulation began. What follows is the wrath of the Lamb being poured out. He points to Psalms 2, where after Jew and Gentile reject the King, they enter perplexity and derision, and then God pours out His vexation and wrath. These events lead to the midpoint of the seven years, with the Antichrist's appearance and Israel permitted to return to temple worship, going back under the Law.