I sent this discussion to a former professor of mine concerning T.F. Torrance's view of God, time and immutability as well as the Trinity doctrine. Wanted to share it with some of you also, who might benefit from a general knowledge of Torrance's Incarnation
I'll try to provide a brief summary of Torrance's book entitled The Christian Doctrine of God: One Being Three Persons (Edinburgh: T & T Clark, 1996). All subsequent references (page numbers) will be taken from his monograph.
Torrance writes that God's being is dynamic (non-static) and thus "unique divine becoming" (237). But how is it possible for God to be "dynamic unchangeableness"?
The author contends that God forever has been Father, Son and Holy Spirit "but not always Creator" (ibid). The Supreme Being produced the cosmos EX NIHILO "in the unlimited freedom of his love" ungrudgingly, uncoerced, that is, by virtue of the fact that He is A SE ESSE (ibid).
Yet when God brought the universe into being through His own Word or Utterance (FIAT LUX), He did not undergo any change at this point (Torrance argues). The cosmos is, in fact, a demonstration of God's immutable and unchangeable nature--although it is not an after-thought, the universe emanates from His "divine life and love" (ibid).
But the "absolutely new [divine] event" (says Torrance) is the Incarnation (238). For while God has always been Father, Son and Holy Spirit and the creation is putatively awe-inspiring evidence of His immutable nature, the living deity of the Bible has not always been incarnate. The LOGOS (the second Person of the Trinity) "became" flesh (hO LOGOS SARX EGENETO) and we beheld his glory: the Son of God possessed the DOXA of an only-begotten son (MONOGENHS hUIOS) and this glory (DOXA) was manifested many times throughout the course of his earthly ministry.
Yet there is a sense in which the Incarnation is also a symbol of God's unchanging nature or essence. Despite God the Son's "crucifixion" and subsequent resurrection to life again--despite the outpouring of the Holy Spirit on those 120 persons gathered at Pentecost in 33 CE--God remains invariant. With Him, the disciple James declares, there is not a variation of the turning of the shadow (James 1:17 NWT). On the other hand, Pentecost might represent a change with respect to the divine life. Torrance notes:
"The transcendent Spirit of God had always been actively present in the world immanently sustaining its continuing relation to God the Creator, but what happened at Pentecost manifested a change not only in the form of his activity but in the mode of his immanence which it is difficult for us to conceive or express. It certainly illuminates for us the changed situation between God and man brought about by the incarnation, but at the same time it brings home to us the fact that what happened at Pentecost was not only quite new in the experience of mankind, but something incomprehensibly new in the life and activity of the eternal God and the mode of his presence to all flesh"(ibid).
To conclude, the upshot of Torrance's analysis of the creative activity of God and the INCARNATIO CHRISTI is that he believes the Triune God is neither the "Unmoved Mover" (Aristotle) nor the "Moved Unmover" (Whitehead)  or, I might add, the "Most Moved Mover" (Pinnock). No, YHWH (according to Torrance) is the Self-moved God, who is immutable with respect to His nature but infinitely mobile, absolutely free, and inexhaustibly new vis-à-vis His divine activity (239).
I now close with this quote from Torrance, who also seems to argue that God is somehow in time as well as eternal. Torrance writes of the living God:
"He is the Self-moved God who is transcendently and majestically free to become one with us in our creaturely existence and even to enter into the depths of our misery and alienation, while remaining he who he always is as the mighty living God, and who is therefore perfectly free and able to redeem and save us from our bondage and degradation" (ibid).
 Colin Gunton describes Whitehead's God as the "Moved Unmover." Torrance also appears to prefer this terminology.