Okay, I don’t know how else to do this, so I am going to transcribe George Hunsinger on Karl Barth and Barth’s understanding of the dialectic between the universality of grace, and the particularity of existential faith (for individual people); and how all of this reflects a kind of tension latent within the pages of the New Testament itself. So this gets at what I am often asked in regard to how I, as an evangelical Calvinist, can sustain a view that believes in universal atonement, but not universal salvation (or Christian universalism). This quote is quite lengthy, but I want something of substance to refer my readers to; and I also want there to be enough context present so you the reader can appreciate (even if you end up disagreeing somehow!) how Barth reconceived of this ongoing problem for the classical theological approach (and I mean the debate between the classical Calvinists and Arminians). I think most people who are classical (indeed all of them) will be dissatisfied with Barth’s approach, because Barth does not give in, and thus resists the human philosophical urge to provide explanation in the kind of classical scholastic kind of rounding off way of things. Let’s get started (caveat: in the future, if anyone wants to challenge how I can maintain the universality and efficacy of saving grace [so called], and the particularity and efficacy of saving faith [so called] the only way I will engage with you around that, is if you actually read this whole post first).
Here is Hunsinger on Barth and the dialectic of the universality of grace and the particularity of faith:
. . . just as the inexplicability of the mode by which the events are related is taken as a sign that in and of itself the created order has no access to ultimate reality.
For reasons such as these, theology must content itself with description and resist the temptation to explanation. In the case of such events it must content itself with describing the mysterious facticity of the that, which facticity intrinsically excludes the possibility of explaining the corresponding how. It is in just such terms that Barth disavows the possibility of explaining the mode by which the events of grace and faith are related. The patter of this relation—its ordered and differentiated unity—can be described, but its mode defies explanation. The pattern is a conjunction of opposites and therefore of irreconcilably antithetical assertions. The unity of grace and faith occurs in such a way that grace is always universal and unconditional in its objective efficacy and validity, yet at the same time faith is always necessary and indispensable in its existential receptivity and freedom. A theology which could explain how this unity occurs as it does or how it occurs as a unity would be explaining the modus operandi of the Holy Spirit.
How gladly we would hear and know and say something more, something more precise, something more palpable concerning the way in which the work of the Holy Spirit is done! How does it really happen that the history of Jesus Christ, in which the history of all human beings is virtually enclosed and accomplished, is actualized, in the first instance only in the history of a few, of a small minority within the many of whom this cannot so far be said, but even in the history of the few typically for the history of the many? How can it really be—the question of the Virgin in Luke 1:34—that there is an actualizing of this history in other human histories? By what ways does God bring it about that in the perverted hearts, in the darkened knowledge and understanding, in the rebellious desires and strivings of sinful human beings—for that is what even the few are—there takes place this awakening, in which they can know Jesus Christ as theirs and themselves as his? How is there really born in them the new human being who knows and recognizes and confesses Jesus Christ? How can there be in history such a thing as Christianity, and human beings who seriously want to be Christians? (IV/1, 648-49 rev., emphasis added)
It is as important and unavoidable to formulate such questions, Barth contends, as it is to leave them unanswered, except for the obviously indispensable appeal to the miraculous and mysterious mode which informs the work of the Holy Spirit as confessed by faith. “The confession credo in Spiritum Sanctum does not tell us anything concerning this How. It merely indicates the fact all this does take place, did take place and continually will take place” (IV/1, 649). Moreover, the evident reticence of the creed at this point is simply a reflection of the reticence of the New Testament itself. “Even the New Testament . . . does not really tell us anything about the How, the mode of his working” (IV/1, 649). Beyond simply describing and asserting the facticity of the Holy Spirit’s working, all questions as to its explanation are consistently repelled. To try to go beyond the New Testament at this point would obviously, Barth believes, be futile.
Barth therefore resolves to work within the terms of this inexplicability. The pattern of dialectical inclusion is used, as indicated, to describe (but not explain) how the history of each and every human being is objectively enclosed in that of Jesus. That same pattern is then used in conjunction with the pattern of actualism to describe (but not explain) how the history of Jesus is in turn objectively included in that of each and every human being. The objective moment of salvation is thereby understood as being at once fully actualized once and for all and yet not encapsulated for imprisoned within its central and definitive form of temporal occurrence. Without compromising this central and definitive form, the objective moment as such assumes secondary and derivative form by actualizing itself in relation to the history of each and every human existence. The actualization of the objective moment of salvation in this twofold form (central and derivative) is (descriptively speaking) a condition for the possibility of its subjective actualization by faith. The existential moment of salvation is thereby understood as occurring entirely within the context established by the objective moment.
The existential moment may therefore not be spoken of as making the the [sic] objective moment real or concrete, as though the objective moment were somehow unreal or abstract as such until the moment of its existential appropriation (a commonplace but ultimately blasphemous way of speaking). Nor may the existential moment be spoken of as effecting a transition from being outside to being inside the objective moment, as though the objective moment did not already include each and every human existence within itself, or as though the existential moment could somehow contribute itself to the objective moment in such a way that the objective would otherwise be deficient. Nor, finally, may the existential moment be spoken of as effecting a transition from being potentially to being actually saved, as though the objective moment were not already in itself the real, valid, and efficacious actualization of salvation for the sake of all. Each of these mistaken ways of speaking makes the event of existential appropriation less incomprehensible and mysterious, Barth believes, than it actually is in its scriptural attestation.
For Barth to think about grace and efficacious faith (saving) must be done through the mystery of godliness,
By common confession, great is the mystery of godliness:
He who was revealed in the flesh,
Was vindicated in the Spirit,
Seen by angels,
Proclaimed among the nations,
Believed on in the world,
Taken up in glory.
There is no wiggle room for trying to construct causal concepts that are both foreign to the text of Scripture’s disclosure, and to the categories revealed in God’s Self revelation in Christ. The conditions and context is descriptively provided for in Christ, and the subsequent understandings of grace and faith therein; but, for Barth, there is no room to move beyond what ends up being a resounding tension between these two ontic and salvific realities; the tension is preserved by the christological tension present, itself, in the hypostatic union of God and humanity in Jesus Christ. We are left in a spot where we can engage in description, and attend to the implications of that as we can; but we have no warranted allowance to move beyond, in order to satisfy our sense of manageability and control in these matters.
As you read this accounting of Barth from Hunsinger, what should have stood out to you most prominently is the role that the vicarious humanity of Christ plays in this. Salvation is objective, actual, efficacious, and realized in Christ for us and with us, in his vicarious humanity. All that needed to be accomplished for salvation for the world (Jn. 3.16) and humanity, has already taken place in the humanity of Christ for all of us. If we want to posit, like classical Calvinism & Arminianism does, that salvation is only real and efficacious when the elect humanity (of individual people, in this account of things) appropriates salvation by faith, then we have just predicated the actualization and realization of salvation upon certain human beings instead of God (even though these human beings were unconditionally elected by God). But I hope you can see the problem with this. It abstracts God’s salvific work from his person in Christ, and makes an aspect of it contingent upon creation and human reception (even if it has been vouchsafed by an artificial, but necessary for this system, positing of an absolute decree of election and reprobation by God). This is a problem for various reasons, which we will have to tease out at a later date (but hopefully you can see how this is a problem on your own).
 George Hunsinger, How To Read Karl Barth: The Shape of His Theology (New York/Oxford: Oxford University Press, 1991), 113-14 [nook edition].
 I Timothy 3:16, NASB, Updated.