We see the Gospel was promised before by the prophets in the scriptures. He is the seed of the Woman to crush Satan’s head eventually. Then as the seed of Abraham, He is to be Multiplied. Christ was multiplied in the resurrection.
"Verily, verily, I say unto you, Except a corn of wheat fall into the ground and die, it abideth alone: but if it die, it bringeth forth much fruit." John 12:24
Since His resurrection, all who believe receive His life. They become His multiplication and His increase. We are the harvest of a seed that was sown in death and resurrection. This is the Body of Christ, the Church. Then, as the Seed of David, we are told that He would possess the throne and be the Son of God
"And when thy days be fulfilled, and thou shalt sleep with thy fathers, I will set up thy seed after thee, which shall proceed out of thy bowels, and I will establish his kingdom. He shall build an house for my name, and I will stablish the throne of his kingdom for ever. I will be his father, and he shall be my son. If he commit iniquity, I will chasten him with the rod of men, and with the stripes of the children of men: But my mercy shall not depart away from him, as I took it from Saul, whom I put away before thee. 2 Sam 7:12-15
Read the book Here ???? Christ As Righteousness Sanctification and Reward