God's calling to Abraham was the work of God the Father. Abraham's original name was Abram which means "an exalted father," and the name Abraham, that replaced this name, means "the father of a great multitude." Both of these names have the basic thought of the father. The first in the Triune God is the Father, and Abraham was the first of the called ones. Abraham was the father of the called ones, and the first of the Triune God is also the Father. The Father is the source of life. He is also the source of plan and purpose. God the Father had a plan, a purpose. Because He had a purpose, He selected and predestinated in eternity past. Eventually, in time, the Father came in to call, justify, accept, and care for the called ones. God the Father's work is to select, predestinate, call, justify, accept, and take care of the called ones. Both selection and pre-destination precede the matter of calling. If you read Romans 9:11, you will see that these two items are found with Jacob. Nevertheless, in Abraham we see nearly all of the experiences that are related to God the Father. This is very meaningful.
Isaac was the son. It is very interesting to see that the second of the Triune God is also the Son. What is a son? A son is one who comes out of the father, who inherits all that the father is and has, and who accomplishes all that the father desires. If you look at Isaac's history, you will find that he was just like this. He was out of the father, he inherited everything of the father, and he worked to accomplish his father's purpose. This is the experience of Isaac, the experience which fits the second of the Triune God, God the Son. The Lord Jesus, as the Son of God, came out of the Father (John 16:28), inherited all that the Father is and has (John 16:15), and accomplished all the Father's will (John 6:38). Isaac's life corresponds to His.
Now we come to Jacob. Jacob, a subtle supplanter, needed more than just the experience of the calling and the inheritance. He mainly needed the dealings to transform him from a man in the flesh to a man in the Spirit. So, it is very meaningful that the third of the Triune God is the Spirit who worked upon the subtle, supplanting Jacob to discipline and transform him into a prince of God. Here, in Jacob, we see regeneration, discipline, transformation, and the growth and maturity in life. All of this is the work of the Spirit. So the God of Jacob should be God the Spirit.
As the transfer of race began with Abraham, passed through Isaac, and was completed with Jacob, so their experiences should be considered as one complete experience. It is implied that the three were one. The Triune God considered them as members of a corporate man for His dealings and for Him to be their God in this way. The last thirty-nine and a half chapters of Genesis are a biography of a corporate person composed of three plus one. If we add together all the different aspects of the experiences of Abraham, Isaac, and Jacob including Joseph, we see a clear picture of the complete experience of the called ones.