In most religions, God is described as "eternal." In particular, in Christianity, God promises eternal life, a promise that seems to require His own eternity.

But how does He know that He is eternal when forever hasn't and can't be reached? How does He know that He isn't going to die a Trillion years from now --perhaps His rate of aging is too small to be noticeable?

In general, how could any eternal being be said to have knowledge of their own eternity? And without it, how can we call them eternal? How can any being be described as eternal, when eternity cannot be reached?

closed as off-topic by Geoffrey Thomas Jan 26 at 10:14

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    If he is God, he is omniscient. – Mauro ALLEGRANZA Dec 31 '18 at 21:22
  • @MauroALLEGRANZA Omniscience is impossible or a fictitious concept, whence God is not omniscient. – Iñaki Viggers Dec 31 '18 at 21:24
  • On the prevailing view of Augustine and Boethius eternal does not mean everlasting, “Eternity […] is the whole, simultaneous, and perfect possession of boundless life” (Consolation, V.VI). So God is not subject to time, and his knowledge is a single act of comprehension, see Eternity in Christian Thought on SEP for other views. – Conifold Jan 1 at 0:24
  • If God is the universe, it is an isolated system. bluffton.edu/homepages/facstaff/bergerd/nsc_111/thermo2.html "In physics and chemistry, the law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be conserved over time. This law means that energy can neither be created nor destroyed; rather, it can only be transformed or transferred from one form to another." en.wikipedia.org/wiki/Conservation_of_energy ...so the physics law of conservation of energy applies to it. – Bread Jan 1 at 2:21
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    The question arises for views that reify time. If time is unreal then God is to be found in the 'Holy Instant' or 'Divine Moment' spoken of by the Christian mystics and indeed mystics everywhere. I feel your question arises from a metaphysically naive view of space-time. . – PeterJ Jan 1 at 14:13

In many interpretations, 'eternal' means more than simply 'everlasting'. For Augustine, eternal means 'not limited by time'.

That means not only that God should exist throughout all of time, but that He existed without time, and has access to all of the past and all possible futures from a point of view outside of the limitations of time. The rationale is that time is a thing, and if God created everything, He created time. If He created time, He is not bound by its laws, because He could simply alter them if He wished.

This is an important aspect of omniscience. It also eliminates the conflict between free will and prophesy. Prophesies can be made from a full view of all time and all possible time, even if there is infinite variation injected by human freedom. It also creates the ability for God to be everywhere at once, including addressing specific objections about who was running the universe while God was incarnated.

  • Even if time were just a measurement and not a thing, God's life expectancy would simply be measured and not limited by it. Regarding prophesy, for it to be fulfilled, either God must intervene in some way or He forecasts the chain reaction of events way into future time. Free will is limited because it was not our will to be born or to die; sometimes our death is caused by external factors such as a fatal accident from a drunk driver or an unexpected fatal disease. – Breakskater Jan 8 at 23:32
  • God did not create everything [that exists]. Or did he create himself? – rus9384 Jan 26 at 10:08
  • @rus9384 Creation is an event. Events take place in time. If God exists without time, it is impossible for 'created' to apply, in this case. So God is not created and does not create himself. This is the classical 'prime mover' argument that is millennia old. If this is just about wording, get over it. – jobermark Jan 26 at 11:19
  • @jobermark Then time itself can't be created, because "Creation is an event. Events take place in time." – rus9384 Jan 26 at 11:47
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    @rus9384 Do you have a real point, or are you just going to ignore the logic because English forces one to use tenses? This is just grammar-flame, and you are just annoyed because you hate religion. – jobermark Jan 26 at 11:51

I would like to revisit your question, now in the form of an answer. First, because I made a typo in my initial comment. Second, because later on I was mischaracterized and explicitly encouraged to post an answer. Here I will avoid question marks so that to the trained eye this looks like an answer rather than an unrelated question.

How does God know that He is eternal?

We cannot ascertain even whether God knows that. This question and the rationale upon which it is premised entail assumptions which warrant some scrutiny.

God must know that He is eternal in order to promise eternal life

Not necessarily. An ordinary person has the ability to make a promise with the intent to deceive (the promissor's mortality does not prevent him from making to others a promise of immortality or of eternal life). A denial that also God possesses the ability to deceive would clearly contradict any consensus that God is mightier or more capable than an ordinary person. Therefore, the sole promise of eternal life does not imply that the promissor knows that he (or He, accordingly) is eternal.

How does He know that He is eternal when forever hasn't and can't be reached?

At the outset, the question itself impliedly negates any and all possibilities that God has reached or can reach the forever. I would not be surprised by the pervasiveness of debate about God's possibilities on this matter, but I will ignore it altogether because I think it sheds no light on the core issue: God's knowledge about His eternity.

The notion that "God knows that He is eternal" inevitably implies at least one of these scenarios:

  • God's information and belief [that He is eternal] is inaccurate; or
  • God is unable to alter or elude the "destiny" designated --arguably by Himself-- to Him: His eternity.

The first scenario would preempt the core question on grounds that He is not eternal. In that case, His alleged knowledge about His own eternity is a doomed presumption.

The second scenario means, in particular, that God would fail each and every attempt of suicide (meaning His suicide) no matter how eagerly and how frequently He tries. That contradicts the notion of His omnipotence. Without omnipotence, God cannot ensure others' eternal life. That implies that His promise of eternal life is unreliable. In turn, the unreliability of His promise(s) weakens His credibility on anything else that He purports to know. Therefore, we cannot ascertain whether He knows about a given topic.

One fundamental problem with absolutist theologies is that their unrestrained idealizations wipe out the chances of a dogma's survival when its philosophical significance is assessed. Anyone is free to disagree --on grounds of faith and mysticism-- with the uncomfortable conclusions reached through the intellect. But it is important not mischaracterize as intransigence (or with reproaches such as "You need to allow people to disagree") when an intellectual assessment leads to conclusions that depart from dogmatic doctrine.

  • Conclusion that God does not deceive does not mean inability to deceive. He can, he just won't (e.g. because he is omnibenevolent). God knowing that he is eternal does not imply either of the two listed alternatives, because both apparently presuppose the non-relativistic idea of absolute time, for example. And so on. We ask users to rely on existing literature in their posts (and give references), rather than on individual reflections, because individual reflections tend to miss what is already discussed there at length. – Conifold Jan 3 at 0:31
  • @Conifold (1) I did not assert God's inability to deceive; quite the contrary. (2) Conceding both God's omnibenevolence and omnipotence is a matter of faith, and it attempts to elude the well known Problem of Evil. (3) In my initial comment to the OP's inquiry, I cited (see the chat) Nietzsche's point that God is dead, but that was one of many of my comments that somebody removed while leaving jobermark's emotional ones intact. (4) Doing philosophy here is on topic. – Iñaki Viggers Jan 3 at 11:35
  • This is one more reason to put substantive points and references into answers rather than comments, and Nietzsche was not focusing on logical coherence like your post. The meta post you linked is outdated, here is a more recent one written by one of our current moderators: we are not doing philosophy here. – Conifold Jan 3 at 22:00
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    @Conifold Thanks for bringing up the more recent meta post. It does conflict with this FAQ, which begins stating that this site also is for "rational analysis of concepts". By way of comparison, in Economics SE there is no meta post in the line of "Friends, we are not economists". There, one can offer answers premised on a rational analysis of concepts/theories in Economics, and that does not hinder the StackExchange [business] profit that this up-to-date meta post purports to second (see its 4th paragraph). – Iñaki Viggers Jan 4 at 20:27
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    The FAQ talks about the scope of topics, not the manner of addressing them. Each SE community sets its own rules, and the current consensus is that SE lacks room, or editorial resources, for doing philosophy of any quality (this is coming from experience from when the rules were looser). Hence, we settled on summaries with pointers elsewhere, there is plenty of rational analysis of concepts to be found in the existing literature. You can bring it up on Meta if you wish. – Conifold Jan 5 at 6:52

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