...if He experiences time sequentially like we do, or does He experience all of time all at once because He created time and is above it?
A tongue-in-cheek answer is "Yes" to both and to all conceivable concepts. But I need to object to the use of the word "experience", although I realize there may not be a better one.
All of our understanding of who God is and what His attributes are, in relation to time, must be restricted to His revelation of Himself in Scripture. All else is less than futile guesswork. And the best place to start that process is probably 2Pet 3:8KJV which teaches that God is outside of, or not affected by, time as we think of it.
What Desert Reign has said on this is, in my opinion, absolutely correct. Time is not an actuality, or a thing, that it can affect anything. It is simply a way we have devised for measuring our grey hairs so to speak. And we have decided that the best way to do that is to base it on God's creative acts regarding day/night and the resulting periods set by the earth, moon and sun.
Sin, on the other hand, is an active reality, from the Fall of Adam, that continues its work of decay in our physical bodies creating more and more 'grey hairs' for us to measure. God does not have 'grey hairs' nor does He sin. To ask the question, then, "How does God experience time?", is to misunderstand how utterly 'other' God is.
To put it another way, how can God 'experience' a human fabrication designed to measure the outworking of sin?
On the other hand, by His grace, He can and does accommodate Himself, in Scripture, to our limited, earthly understanding of how things work and will speak to us in linear terms for our ease of understanding His precepts. Consider Gal 4:4KJV to appreciate how He is Lord over even that which does not exist, working with it, without getting His hands dirty, to fulfill to the letter all judicial and prophetic requirements with only our good in mind.
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