John Calvin is an important figure for Protestant theology. If we can move past all the polemics that are associated (usually, wrongly) with his name, and actually engage with his theological offering; what the reader will find is a rich storehouse of theological reflection that is highly 
Christ concentrated. That’s what I intend to do with this post; I want the reader to be turned onto an aspect of Calvin’s soteriology that has enriched me greatly since the first time I was exposed to it. I am referring to what Calvin calls Double Grace (DUPLEX GRATIA). It is this soteriological frame, that for Calvin, is deeply grounded in a Christological focus; to the point that when reading his development of it, at points, you might mistake him for Karl Barth or Thomas Torrance. In this teaching Calvin thinks both justification and sanctification from nowhere else but the vicarious humanity of Jesus Christ. For Calvin, in order for salvation to inhere for the person, he/she must be in participation with Christ’s humanity by the regenerating work of the Holy Spirit. In order for eternal life to obtain for the individual, that person must be in union with Christ (unio cum Christo); since Christ alone has won the salvation of God in the work He accomplished through incarnation and atonement. This conceptuality, by the way, is a locus classicus for what we are attempting to offer with our notion of Evangelical Calvinism.
Here Calvin in his 1541 French edition of his Institutes of the Christian Religion explains what he means when referring to ‘double grace.’
It seems to me that I have previously explained carefully enough how it is that there remains to people only one refuge for salvation, which is faith, because by the law they are all cursed. I believe that I have also sufficiently discussed what faith is and what graces of God it communicates to people and what fruit it produces in them. Now the summary was that by faith we receive and possess Jesus Christ as He is presented to us by God’s goodness, and that in participating in Him we have a double grace. The first grace is that when we are reconciled to God by His innocence, instead of having a Judge in heaven to condemn us we have a very merciful Father there. The second grace is that we are sanctified by His Spirit to meditate on and practice holiness and innocence of life. Now as for regeneration, which is the second grace, I have said what seemed to me necessary. Justification was more lightly touched upon, because we had to understand what the good works of the saints are, which is a part of the question we must treat next.[1]
Of significance, per my impression, is the way Calvin thinks of these ‘two graces’ as embodied in Jesus Christ first. So, if we were to think this in terms of an ordo salutis (‘order of salvation’), we might think of it in this way: 1) Justification and Sanctification first obtain in Christ’s life for us, and 2) Justification and Sanctification second obtain for all those, who by faith, are in participation with Christ and His humanity for us. To frame salvation from this accent gives it a decidedly filial feeling, such that other sorts of theories of salvation, the ones that have juridical or forensic frames, are put into relief; or out to pasture where they should be. Not wanting to overread Calvin here, I wouldn’t want to make it sound like Calvin was a crypto-Barthian, but I do think the personalist and even existential conceptions present in Barth’s soteriology can be found in Calvin—to a degree. In order to illustrate this ‘feeling,’ in regard to the filial sort of salvation Calvin is offering, let me share from him further. Here you will notice the sharp emphasis Calvin lays on being in Christ; I take this to be a further development of his duplex gratia as that is given form in Christological repose.
Now in speaking of the righteousness of faith scripture leads us to quite another place; that is, it teaches us to turn our attention away from our works to regard only God’s mercy and the perfect holiness of Christ. For it shows us this order of justification: that from the beginning God receives the sinner by His pure and free goodness, not considering anything in him by which He is moved to mercy except the sinner’s misery, since He sees him completely stripped and empty of good works; and that is why He finds in Himself the reason for doing him good. Then He touches the sinner with a feeling of His goodness so that, distrusting everything he has, he may put the whole sum of his salvation in the mercy which God gives him. That is the feeling of faith, by which a person enters into possession of his salvation: when he recognizes by the teaching of the gospel that he is reconciled to God because, having obtained the remission of his sins, he is justified by means of Christ’s righteousness. Although he is regenerated by God’s Spirit, he does not rest on the good works which he does, but is reassured that his perpetual righteousness consists in Christ’s righteousness alone. When all these things have been examined in detail, what we believe about this matter will be easily explained. They are better digested if we put them in a different order than we have proposed them; but one can scarcely fail to grasp these matters provided that they are recounted in order in such a way that everything is well understood.[2]
What we have in Calvin is a robust, and I’d argue, Pauline development of what an ‘in Christ’ theory of salvation entails. The focus, for Calvin, unlike so much later ‘Calvinist’ and ‘Puritan’ theology, is not primarily on the recipient of salvation, but on the ‘cosmic’ Christ. Let me qualify this: when reading Calvin we can certainly find conceptual matter that sounds like what developed later in ‘Calvinism’ and the sort of ‘practical syllogism’ soteriology that the Puritans (like William Perkins) developed. But, I’d contend, and have here, that Calvin tends to contradict his Christ conditioned superstructural foundation when he presents us with a hidden decree of reprobation and ‘temporary faith.’
In the main Calvin is a richly and profoundly Christ funded theologian who seeks to find Christ in just about every nook and cranny conceivable; particularly when that comes to a doctrine of salvation. He isn’t a Barth or Torrance, come on, he lived in the 16th century; but in an antecedent form, under the theological conceptual pressures he inhabited, he (along with Luther) is as close as we might get to what latterly developed under the Barthian regimen of theological endeavor. I commend Calvin’s double grace soteriology to you; one that is decidedly grounded in the singular person of Jesus Christ.
[1] John Calvin, Institutes of the Christian Religion: 1541 French Edition, trans. by Elsie Anne McKee (Grand Rapids, Michigan: William B. Eerdmans Publishing Company, 2009), 318 [emboldening mine].
[2] Ibid., 320-21 [emboldening mine].