All of this talk about “simplicity” and “inseparable operations” can leave folks a little unsure as how to speak Biblically. Surely the Bible presents the Son as doing things that the Father does not do, and just as surely, it must present the Spirit doing works that the Son does not do. How can we reconcile this with our Trinitarian commitments?
Lewis Ayres offers up this explanation:
Closely linked to the doctrines of divine simplicity and inseparable operation is the practice of appropriation. Appropriation is the practice of attributing to one divine person an attribute or action that is common to the Godhead and thus to all divine persons: because the persons work inseparably in the context of the divine simplicity we frequently speak about something as characteristic of a divine person although it is in fact equally true of all divine persons. Appropriation is, for Pro-Nicenes, an important habit of Christian speech because it is central to Scripture’s own speech about the divine persons. Appropriation is sometimes presented as an ‘Augustinian’ doctrine: in fact, Augustine’s clarity about the doctrine- which may be seen in Chapter 15- is simply the clearest statement of a common pro-Nicene principle.
~ Nicaea and Its Legacy pg. 297
We must also keep in mind the distinction between archetypal and ectypal phenomena. What appears to us to be the work of a singular person, for it is occurring within our created world, involves all three persons in their infinity, however incomprehensible that may be.