In their articulation of the doctrine of God’s eternal election, early modern Reformed theologians were very careful to express the fact that God did not elect his chosen people in the abstract, but rather God’s election was always founded on Christ as the only mediator. Election is always “in Christ” (in Christo) and “on account of Christ” (propter Christum). The prominent Reformer Wolfgang Musculus (1497-1563), who served as professor of theology at Bern, explains this in his Loci Communes Sacrae Theologiae (1561 edition, p. 249-250, own translation):
Although it is evident that our election is not in any respect to be attributed to any quality or worthiness in us, but only to the pleasure, will, and purpose of God, and that we cannot identify any cause besides his immense goodness for why it was bestowed on us, yet it is not at all proper for us to believe that it is not dependent on an intermediary in whom, before the foundation of the world, the majesty of God chose humans unto himself, who would be so different to him in nature, and who would be wretched in so many ways. For this election is instituted in such a way that it cannot permit the separation of the elector from the elect. For just as reprobation excludes any connection between those who are reprobated and the one who reprobates them, so election joins the elect with the elector, and this conjunction of two very different natures, of God and of man, could not be made without the unifying link of some mediator.
Heat and cold cannot be united, except in some mean which accommodates them both; so it was much less possible that man, who is colder than ice, should without some mediator be united to God, who is a consuming fire. These things are clear to all, except to those who, considering neither the eminence of the divine majesty nor the abjectness of human infirmity and corruption, fancy that they can be conjoined to God – I know not by what rites or works – without a mediator.
Now, who that mediator is, in whom God has chosen us before the foundation of the world and has united us unto himself by a perpetual conjunction, the Apostle diligently expresses to the Ephesians (1:3-4), saying: “Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ: According as he hath chosen us in him before the foundation of the world.” And so we are chosen by God the Father in Christ his Son in an eternal election before time, that is to say, the world was only made afterwards.
In this we see that it was so determined from eternity, that we should be saved through Christ the mediator, the Son of God. And it was so predestined that the same eternal Word should be born in his time in our flesh, so that by the very same one by whom we were to be created, in the same we were also elected to be redeemed and saved. In this way our faith in our mediator and saviour Christ has altogether a most ancient foundation, that is to say, eternal, and laid down before all times and ages. In this way we were also in Christ before the world was made, that is to say, by virtue of this eternal election. He did not elect us as being in him before we were chosen, but he elected us so that we may be in him and be saved through him.
Chrysostom takes en autō [in him] to be the same as di’ autou [through him]. But, in my judgment, just as it is not proper for us to say of Christ, as our mediator, that he is our elector, so it is not proper to say that we have been elected by him. But it is proper to say, as the Apostle does, that we have been elected in him by God the Father. God elected us on account of Christ, he elected us in Christ: On account of Christ, as mediator; in Christ, as the head of the elect or those who are to be saved. And it was not at his birth according to the flesh that he was first made the mediator, head, and saviour of the elect, but he was constituted as such from eternity by the Father, and we were chosen in him and on account of him before we were born. When God determined the head or mediator of those who would be saved, he simultaneously also determined those that would be saved by him as his members, which determination the Apostle calls the election made in Christ.
Wherefore we must not consider this mystery of our election by halves or piecemeal, but in full and as a whole, with both these parts joined together, with sincere faith and highest devotion, admiration, and gratitude to Christ our mediator, head, and saviour. And for the confirmation of the certainty of our salvation in our hearts, we must also consider how our election is grounded and built upon the same counsel of God, the same eternity, and indeed the same strength as the mystery of Christ.