The Redeemer and predestination.

John Calvin has written:

“Should any one object, that in this there is nothing to prevent the same Christ who redeemed us when condemned from also testifying his love to us when safe by assuming our nature, we have the brief answer, that when the Spirit declares that by the eternal decree of God the two things were connected together, viz., that Christ should be our Redeemer, and, at the same time, a partaker of our nature, it is unlawful to inquire further. He who is tickled with a desire of knowing something more, not contented with the immutable ordination of God, shows also that he is not even contented with that Christ who has been given us as the price of redemption. And, indeed, Paul not only declares for what end he was sent, but rising to the sublime mystery of predestination, seasonably represses all the wantonness and prurience of the human mind. "He has chosen us in him before the foundation of the world, that we should be holy and without blame before him in love: having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will, to the praise of the glory of his grace, wherein he has made us accepted in the Beloved: In whom we have redemption through his blood," (Eph. 1: 4-7). Here certainly the fall of Adam is not presupposed as anterior in point of time, but our attention is directed to what God predetermined before all ages, when he was pleased to provide a cure for the misery of the human race. If, again, it is objected that this counsel of God depended on the fall of man, which he foresaw, to me it is sufficient and more to reply, that those who propose to inquire, or desire to know more of Christ than God predestinated by his secret decree, are presuming with impious audacity to invent a new Christ. Paul, when discoursing of the proper office of Christ, justly prays for the Ephesians that God would strengthen them "by his Spirit in the inner man," that they might "be able to comprehend with all saints what is the breadth and length, and depth and height; and to know the love of Christ which passeth knowledge," (Eph. 3: 16, 18); as if he intended of set purpose to set barriers around our minds, and prevent them from declining one iota from the gift of reconciliation whenever mention is made of Christ. Wherefore, seeing it is as Paul declares it to be, "a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners," (1 Tim. 1: 15), in it I willingly acquiesce. And since the same Apostle elsewhere declares that the grace which is now manifested by the Gospel "was given us in Christ Jesus before the world began," (2 Tim. 1: 9), I am resolved to adhere to it firmly even to the end. This moderation is unjustly vituperated by Osiander, who has unhappily, in the present day, again agitated this question, which a few had formerly raised. He brings a charge of overweening confidence against those who deny that the Son of God would have appeared in the flesh if Adam had not fallen, because this notion is not repudiated by any passage of Scripture. As if Paul did not lay a curb on perverse curiosity when after speaking of the redemption obtained by Christ, he bids us "avoid foolish questions," (Tit. 3: 9). To such insanity have some proceeded in their preposterous eagerness to seem acute, that they have made it a question whether the Son of God might not have assumed the nature of an ass. This blasphemy, at which all pious minds justly shudder with detestation, Osiander excuses by the pretext that it is no where distinctly refuted in Scripture; as if Paul, when he counted nothing valuable or worth knowing "save Jesus Christ and him crucified," (I Cor. 2: 2), were admitting, that the author of salvation is an ass. He who elsewhere declares that Christ was by the eternal counsel of the Father appointed "head over all things to the church," would never have acknowledged another to whom no office of redemption had been assigned.”

(Calvin, John. Institutes of the Christian Religion, Grand Rapids, MI: Wm. B. Eerdmans Publishing, 1998, p. 404-405.)