It pleased God to ordain His Son for what reason?

8:1 It pleased God, in His eternal purpose, to choose and ordain the Lord Jesus, His only begotten Son, to be the Mediator between God and man,[1] the Prophet,[2] Priest,[3] and King,[4] the Head and Savior of His Church,[5] the Heir of all things,[6] and Judge of the world:[7] unto whom He did from all eternity give a people, to be His seed,[8] and to be by Him in time redeemed, called, justified, sanctified, and glorified.[9]

Here G.I. Williamson in his study of the WFC summarizes saying,

“This section of the Confession teaches us (1) that God has, from eternity, chosen a definite number of Adam’s posterity to be saved through the redemptive work of Christ, (2) that he also, from eternity, promised to give these elect persons to Christ as the reward for his suffering, (3) that Christ engaged to perform and suffer all that was necessary to that end, (4) that this messianic work required Christ to be the prophet, priest, and king of his elect people as head and Savior of the Church, and (5)that he must also be heir and judge of the world.”

What does this mean? is that Jesus, the Mediator, governs over all creatures and all their actions for His own glory. Submission is due to Him from all men and angels. All men, in every possible relation and condition, are under obligation to promote His gracious purposes according to His law. The hole angels minister, under His direction, to the heirs of salvation.