What did God do after four thousand years of varying types of responsibility?
God did something totally different: He fulfilled His Genesis 3:15 promise. At the fullness of time, according to His exact schedule, the Messiah was born in Bethlehem. This was the crucial turning point in God's timetable, occurring after the long period of varying responsibility.
Les explains that Israel lived under those circumstances until the work of the cross was finished, but the work of the cross could not be finished until Christ was first born at Bethlehem. After four thousand years of varying types of responsibility, God suddenly did something totally different. It began with the fulfillment of a promise He made in Genesis chapter three, verse fifteen. In spite of four thousand years of various activities, when the fullness of the time was come—according to God's schedule, at the exact right day, hour, and year—the Messiah was born in Bethlehem. Les notes this is the Christmas story, referring to Christ's birth, and Paul does not have to rehearse all the details of Joseph and Mary because it was already implied and prophesied. The reason it happened was that it was in God's timetable.
And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel.