In Abraham we first read about the faith of people being a key component of that plan. Abram believed the Lord, and He credited it to Him as righteousness. Move along in the Old Testament through into the book of Exodus and you see God make formal covenant and promises with the new nation of Israel. I am your God and you are my people. History rolls on.
Temptations are great.
There are struggles. But then we encounter the life of David. Again echoes of the very first promise are heard. The Plan still is on the move. We hear of a Son of David.