As a prelude to what I plan to post for Good Friday, I would like to offer Karl Barth’s summary of what St. Augustine called the orthodox faith of the catholic [universal] church, namely, that as the being of the Triune God is indivisible, so are his works indivisible. Just as we cannot conceive of the Father, Son, and Holy Spirit as separate beings or Gods unto themselves, but only as one God with one being, so also we cannot conceive of the works that the Father, Son, and Holy Spirit accomplish as being separate acts unto each person. Thus, for example, we cannot say that only the Father was the Creator, or that only the Son is the Savior, or that only the Spirit is the Sanctifier, for in all the works of creation, salvation, and sanctification, each person of the Trinity is fully united with the others in act just as they are in being.
Barth explains this somewhat technical but highly important concept as follows:
Just as Scripture is to be read in context as the witness to God’s revelation, just as, e.g., Good Friday, Easter and Pentecost can only say together what they have to say, so we must say that all God’s work, as we are to grasp it on the basis of His revelation, is one act which occurs simultaneously and in concert in all His three modes of being. From creation by way of revelation and reconciliation to the coming redemption it is always true that He who acts here is the Father and the Son and the Spirit. And it is true of all the perfections that are to be declared in relation to this work of God that they are as much the perfections of the Father as of the Son and the Spirit. [By appropriation] this act or this attribute must now be given prominence in relation to this or that mode of being in order that this can be described as such. But only [by appropriation] may this happen, and in no case, therefore, to the forgetting or denying of God’s presence in all His modes of being, in His total being and act even over against us….
From the eternity of the relation of the Father and the Son, in which that of the relation of both to the Holy Spirit is also contained, it necessarily follows first that not only God the Father is to be claimed as the Creator and as our Father, and that God the Father is not only to be claimed as the Creator and as our Father. We have said above that the use of the name Father for this relation and act of God ad extra is a derived and improper use. Revelation in so far as it is the revelation of God the Creator and our Father, and in so far as this its content is not to be separated from its form as revelation in Jesus, leads us to the knowledge of God as the eternal Father. But in this very knowledge we cannot separate the Father from the Son and from the Holy Ghost. In this knowledge, then, there necessarily becomes plain to us the purely relative significance of the way of isolation on which we have reached this knowledge. It implies an “appropriation” (cf. § 9, 3) when by isolation we regard specifically God the Father as the Creator and as our Father and when we regard God the Father specifically as the Creator and as our Father. The triunity does not mean that three parts of God operate alongside one another in three different functions. [The external works of the Trinity are undivided], as also the essence of God is a single and undivided essence…
Thus not only the subject of the first article of the Creed is the Father Almighty, Creator of heaven and earth, but with Him, in the order and sense pertaining to each, the subjects of the second and third articles too. And again the subject of the first article is not only the Father Almighty, Creator of heaven and earth, but also, again in the appropriate order and sense, the subject of reconciliation like the subject of the second article and the subject of redemption like that of the third article. Not the Father alone, then, is God the Creator, but also the Son and the Spirit with Him. And the Father is not only God the Creator, but with the Son and the Spirit He is also God the Reconciler and God the Redeemer. The very knowledge of the intratrinitarian particularity of the name of Father is thus a guarantee of the unity of God which would be endangered by regard for the particularity of God’s revelation as the Creator and our Father if this were not guided by this apparently—but only apparently—very speculative intratrinitarian insight. Because God is the eternal Father as the Father of the Son, and with Him the origin of the Spirit, therefore the God who acts in reconciliation and redemption, and who reveals Himself as the Reconciler and Redeemer, cannot be a second and third God or a second and third part of God; He is and remains God [one and indivisible] in His work as in His essence.
Barth notes here that while it is possible and legitimate, on the basis of Scripture, to attribute (i.e. appropriate) certain acts to one specific person of the Trinity, it must be kept in mind that this way of speaking should not be thought to imply that the other two persons are uninvolved in that work. Any appropriation of the divine works to one person of the Trinity is a means by which Scripture stoops to human understanding in order to helps us comprehend the incomprehensible, so in no way should it be hardened into a clear-cut division. “For whatever the Father does, that the Son does likewise” (John 5:19). Thus, the Father, Son, and Spirit are indivisibly united in their works just as they are in their essence.
Although it may not be immediately apparent, this doctrine of “inseparable operations” has massive implications for the rest of theology, not least for the atonement and election. Without going into great detail, suffice it to say that we must theologize according to following rule: the person and work of Jesus Christ in history corresponds completely and without remainder to the being and will of God in eternity. We cannot, therefore, attribute to God’s eternal design some intention that is not fully manifested in Christ, particularly in his death and resurrection. Thus, the doctrine of inseparable operations establishes an indivisible link between atonement and election, as it also interweaves together all other aspects of Christian theology. Interpreting Scripture and doing theology in terms of this key doctrine is what thinking theo-logically is all about.
So tomorrow: what does inseparable operations mean for our understanding of the atonement?
 Karl Barth, Church Dogmatics I/1 (London; New York: T&T Clark, 2004), pp.374-375, 394-395.