•• How can the Son be eternally begotten “today” and also have this begetting be specially associated with the Resurrection and/or the Ascension? ••
This was something I never understood myself, until I spent several months meticulously working my way forward through a progressing metaphysical argument arriving at trinitarian theism (though this element doesn’t require reference to a 3rd Person of God). This leaves me at something of a disadvantage: trying to give people who haven’t gone through the same exercise with the same results, an idea of how I found the topics to link together.
The most I can say for now, is that I found that the submission of God self-begotten to God self-begetting completes the circuit of God’s self-existence; while the Father isn’t begotten from the Son, the unity of God’s own self-existence does depend on the choice of the Son to submit to the Father in love. As Jesus says in the scriptures (especially in GosJohn), the Son goes forth from the Father and returns to the Father. Analogically, the raising of the Son by the Father becomes linked to the Son being the very power of God the Father, seated analogically (on a single throne, notice) at God’s right hand. The Ascension of the risen Christ fulfills in a ‘minor key’ what the Father is always doing for the faithful Son in the faithfulness of the Son.
The same is true of the Resurrection, but here we begin delving into the mystery of creation itself. No system exists beside God (ontologically speaking, at the same level of ultimate existence) for God to create into, and God cannot even create a not-God system of that sort without there being a shared overarching system on which they both must be dependent. Whatever not-God entity or system that God generates must be wholly dependent upon God; and in the absence of any field of endeavor already existing in some independent fashion, the field must be made by God through God’s own self-sacrifice.
Putting it another way, any action of God at all apart from the generation of Himself, God, must necessarily involve the generation of that which is not-God: creation, distinct from begetting. And this will necessarily involve the willing self-sacrifice of the action of God. The Son’s eternal sacrifice to the Father for the sake of the unity of God’s own self-existence, obtains its first variation in the Son’s sacrifice as the foundation of the world, the natural not-God system of reality. It is a different descent into death; and from death, into life, not for God (that eternal action hasn’t ceased and still continues) but for that-which-is-not-God.
The circuit of this action must be fulfilled, not so that the not-God creation may become God: for that would be to undo the creation altogether! But it must be fulfilled so that God may be all in all; as fundamentally God already is, immanently as well as transcendently. But the raising and imbuing of non-sentient created material into derivative sentience is the first major step in this direction; and, where the derivative sentiences may rebel, their restitution and reconciliation must be acted toward as well (without merely un-creating them). Whether there is rebellion or not, however, it makes intrinsic sense for the Son, the self-begotten action of God, to participate even more intimately in this process than, as joint creator with the Father, the Son is already doing. The incarnation, the sacrificial death, and the resurrection of the Son Incarnate, fits into this larger thematic action of the Son. Where the sin of derivative children of God is a reality, this sacrifice of the Son will not only be submitted to be an occasion, the chief enactment, of such sin (for in sinning we abuse the grace of God in any case, which He permits for sake of His love for us); but the sacrifice and raising of the Son will be the cardinal point, the turning point, the deepest action of God, of His total action toward the fulfillment of creation: that God will be all in all (without the all simply un-creating back into God).
Once I realized this, then I suddenly understood why St. Paul could be inspired to say that the Resurrection and/or Ascension of the Son could be considered specially as the begetting of the Son “today” by the Father.
(The mythopoeic part of me also recognized the propriety of the Son being placed in the heart of the earth and then rising, as a completion of the “begetting” of the Son. For just the same had been done, in principle, in the womb of His mother. Even the descent of the sun beneath the land as the start of the Jewish day, in apparent contravention to all visual logic, fits this theme. The Day of the Lord has begun, even though we still have all the darkness of death yet to live and die through. But God Himself goes before us. God Himself goes down into the dust, dying as far as any person can die, not first so that we will not die, but so that our deaths may be like His.)