What is the whole purpose of what God began doing at creation?
The whole purpose of what God began at creation, when He created Adam and Eve, is to bring the world to a knowledge of the crucified, buried, and risen Christ. For us today, this is the epitome of everything God began, though Peter did not yet know it because God had not revealed it.
Les explains that for us today, this is the whole epitome of everything that God began to do when He created Adam and Eve: to bring the world to a knowledge of the crucified, buried, and risen Christ. But Peter did not know that yet, because God had not revealed it; it was still secret. Everything is done for a purpose, to teach us something even today. The unfolding of God's plan includes progressively revealing His purposes, and at that time the full message of Christ's death, burial, and resurrection had not yet been made known to Peter.