Why did God call Abraham and make a nation from him?
God called Abraham and made a nation from him because He was initiating a new redemptive plan for mankind. After humanity's failure, God chose one man to create a nation, work through and prepare them, and through them take salvation back to the whole mainstream of humanity. This Abrahamic covenant became the bedrock of God's redeeming work.
Les teaches that after 2,000 years of a hopeless race of humanity coming out of Adam, destroyed in the flood, and going back into paganism at the Tower of Babel, God at 2,000 B.C. said He would do something totally different. He called out one man, Abraham, and from him brought a little nation. God promised Abraham a nation of people, a geographical area of land, and at the appropriate time their king, government, and kingdom, so Israel could be the evangelization of the nations. Through this prepared nation, God would take salvation back to the whole mainstream of humanity. Even though Israel rejected their king, God has not given up on them, as Peter still pleads with Israel in Acts.