Why could the Godhead put the whole plan together in eternity past?
The Godhead could put the whole plan together in eternity past because of foreknowledge. Foreknowledge made the eternal redemptive plan possible. Scripture distinguishes foreknowledge from predestination, stating that the believing remnant of Jews was elect according to foreknowledge, not according to predestination.
Les explains that the crucifixion had to occur because it too was in the predeterminate counsel of God, and the whole Godhead is involved in this tremendous work of redemption. The other word he points out is foreknowledge. Way back in eternity past, they put the whole plan together, and the reason they could put it together was the foreknowledge. In First Peter chapter 1, Peter writes to strangers scattered throughout Pontus, Galatia, Cappadocia, Asia, and Bithynia. Verse 2 calls them the elect, the believing end of the Jews, elect not according to predestination but according to foreknowledge. Les says that distinction makes all the difference in the world.