The Leitsatz (thesis statement) for §31 states: "The divinity of the freedom of God consists and confirms itself in the fact that in Himself and in all His works God is One, constant and eternal, and therewith also omnipresent, omnipotent and glorious."
In paragraph §31 ("The Perfections of the Divine Freedom") and subsection §31.3 ("The Eternity and Glory of God"), Barth now turns his attention to the final pair of perfections - the eternity and glory of God.
As Barth suggests, eternity is no mere opposite of time though, it includes it:
There lies before us a consideration of God’s freedom in a third and final grouping of its perfections. Its divinity consists and confirms itself in the fact that in Himself and in all His works God is eternal and therefore glorious (608).Barth begins with God's eternity, which he notes, is a perfection of His freedom (608). Eternity is not an infinite extension of time both backwards and forwards, rather, it is the simultaneity of beginning, middle, and end - God's pure duration! (608). In this duration, God is free. Really free to be constant. The reason why He is free to be constant is that time has no power over Him (609). As the one who endures, He has all power over time. He is God in eternity, but this duration is exclusively His being (609). Eternity is a description of the being of God.
As Barth suggests, eternity is no mere opposite of time though, it includes it:
Nothing less than the assurance of faith and the possibility of trust in the enduring God depends on the fact that time is not excluded from His duration but included in it, so that we in our time may recognise and honour His time, the time given us by Him. This is just what we may and ought to do. We have seen again and again that God is alive. His unity does not exclude but includes multiplicity and His constancy movement. And God does not first create multiplicity and movement, but He is one and simple, He is constant, in such a way that all multiplicity and movement have their prototype and pre-existence in Himself. Time, too, pre-exists in this way in Him, in His eternity, as His creation, i.e., with space, the form of His creation. The form of creation is the being of God for a reality distinct from Himself. But the form of God’s being for us and our world is space and time (612).To rightly understand the relationship between eternity and time, we must realize the relationship of God towards the creature:
Again, a correct understanding of the concept of eternity is reached only if we start from the other side, from the real fellowship between God and the creature, and therefore between eternity and time. This means starting from the incarnation of the divine Word in Jesus Christ. The fact that the Word became flesh undoubtedly means that, without ceasing to be eternity, in its very power as eternity, eternity became time. Yes, it became time. What happens in Jesus Christ is not simply that God gives us time, our created time, as the form of our own existence and world, as is the case in creation and in the whole ruling of the world by God as its Lord. In Jesus Christ it comes about that God takes time to Himself, that He Himself, the eternal One, becomes temporal, that He is present for us in the form of our own existence and our own world, not simply embracing our time and ruling it, but submitting Himself to it, and permitting created time to become and be the form of His eternity (616).In Jesus Christ, God Himself was able to be temporal (617). Barth favors a threefold form of the temporality of God's eternity: pre-temporality, supratemporality, and posttemporality; meaning, God manifests Himself as the One who precedes time, accompanies time, and present after time (619). God's eternity is a "readiness" for time (620). Pre-temporality, supra-temporality and post-temporality are equally God’s eternity and therefore the living God Himself (638).
This is the last thing which we have to emphasise in connexion with the concept of eternity. Like every divine perfection it is the living God Himself. It is not only a quality which He possesses. It is not only a space in which He dwells. It is not only a form of being in which He shares, so that it could belong, if need be, to other realities as well, or exist apart from Him in itself. We cannot for one moment think of eternity without thinking of God, nor can we think of it otherwise than by thinking of God, by knowing Him and believing in Him and obeying Him—for there is no knowledge of God without this—by loving Him in return when He has first loved us. Eternity is the living God Himself. This radically distinguishes the Christian knowledge of eternity from all religious and philosophical reflection on time and what might exist before and after time. It distinguishes it from all speculations about different aeons, all the mythologies of past, present and future worlds, their essence and their relations to one another. The Christian knowledge of eternity has to do directly and exclusively with God Himself, with Him as the beginning before all time, the turning point in time, and the end and goal after all time. This makes it a complete mystery, yet also completely simple. In the last resort when we think of eternity we do not have to think in terms of either the point or the line, the surface or space. We have simply to think of God Himself, recognising and adoring and loving the Father, the Son and the Holy Spirit. It is only in this way that we know eternity. For eternity is His essence. He, the living God, is eternity. And it is as well at this point, in relation to the threefold form of eternity, to emphasise the fact that He is the living God (638-639).
