John Calvin Commentary Ephesians 1:9

"making known unto us the mystery of his will, according to his good pleasure which he purposed in him" — Ephesians 1:9 (ASV)

Having made known to us the mystery of his will. Some were alarmed at the novelty of his doctrine. With a view to such persons, he very properly terms it a mystery of the divine will, and yet a mystery which God has now been pleased to reveal. As he formerly ascribed their election, so he now ascribes their calling, to the good pleasure of God. The Ephesians are thus led to consider that Christ has been made known, and the gospel preached to them, not because they deserved any such thing, but because it pleased God.

Which he hath purposed in himself. All is wisely and properly arranged. What can be more just than that his purposes, unknown to men, should be known to God alone, so long as he is pleased to conceal them, — or, again, that it should be in his own will and power to fix the time when they shall be communicated to men? The decree to adopt the Gentiles is declared to have been until now hidden in the mind of God, but so hidden, that God reserved it in his own power until the time of the revelation. Does anyone now complain of it as a new and unprecedented occurrence, that those who were formerly without God in the world, (Ephesians 2:12) should be received into the church? Will he have the audacity to deny that the knowledge of God is greater than that of men?