Omniscience is an article of faith among people across various faiths that hold faith in the Supreme God. Omniscience baffles reason. How can God know all things beyond time: things that were, things that are, and things that will be?
I know your works, tribulation, and poverty (but you are rich); and [I know] the blasphemy of those who say they are Jews and are not, but [are] a synagogue of Satan. Do not fear any of those things which you are about to suffer. Indeed, the devil is about to throw [some] of you into prison, that you may be tested, and you will have tribulation ten days. Be faithful until death, and I will give you the crown of life. (Rev 2:9-10)
The biggest challenge comes in the form of the objection:
1. Knowledge is cognizance of something that exists.
2. The future doesn’t exist yet.
3. Therefore, one cannot know the future.

There have been various reactions to this and attempts to try to explain omniscience of future events. Some subscribing to the eternalist theory of time (the view that events already exist at various points of time and that time is tenseless; i.e. there is actually no past or present or future) think that eternalism is helpful in explaining that divine foreknowledge doesn’t contradict reason, for future events already exist in the temporal-points of time. However, in experience, we know that we are not already there in the future while we are still here. Thus, time-fictions that imagine oneself traveling to the past or the future and being able to see oneself as another self only cash on the imagery of a realistic video playback. One can go to the past in the same way that one can go back to a time frame in a video and playback from there, they imagine; the exception in this reality playback: one can interfere. Similar is the imagination about the future. Of course, this involves the paradox of going back and killing oneself and yet being able to survive in the present. Some have even tried to suggest theories about several parallel universes and possibility worlds, which look interesting to the mind, but pose an interesting plurality. Of course, this could be one area where fiction allows for man to imagine a unity of being and yet a plurality of persons at the same time. For instance, in this imaginary time-trip, I find myself in 2010 at a University campus where I am presenting a paper. I (standing under a tree) see myself (near another building) on way to the Seminar hall inside. There is a duality here. I am standing under a tree and yet I am near another building on way to the Seminar hall. It doesn’t appear very problematic to those who think this could be possible in time travel; because, at least from one point in time (2016), I have gone missing. Nevertheless, it doesn’t seem impossible to the imagination to allow two different persons of the same one being in the same place with two different personalities at the same time. Also, in this view, the present is meaningless; for, 2010 is as really present to me (both me standing under the tree and myself on the way to the Seminar hall) in that framework as 2016 was real to me “earlier” (i.e. in my past). At the same time, due to the possibility of time-travel, I (2016) and myself (2010) are both at the same place and the same time, fictionally speaking. This temporal imaginative permission is incredulous. This violation of reason, perhaps, should forbid us trying to question how the eternal Godhead cannot be three persons in His eternal being.

However, that God sees the future and knows everything is an article of faith. The eternalist (e.g. block universe) theory, itself is an assumption that seeks rational evidences. I do not subscribe to the eternalist view because it gives a picture of a fixed-history. Events are fixed in the timeline of history. Of course, we can imagine an infinite number of possibilities by bringing time-travel into the equation (like the one we imagined above). However, this will turn our experience into a framework of determinism. What happens will happen as if it has already happened. But, then this would contradict the possibility of truth, since truth will become subject to determinism as well, in which case, truth loses the attribute of transcendence and freedom. If so, how can one know if this idea of determinism itself is true?

Consequently, the conviction that God knows the future and sees it is rationally inexplicable. With regard to the block universe argument, this immediately raises the question of how God can see the universe as a block (from the beginning to the end of time) and yet be able to atemporally be involved in it. That, of course, poses the rational-empirical conflict. Reason’s God is atemporal but His actions have to be located temporally. Also, to state that God has created the universe with all His actions included in it from the beginning to the end will turn the world deterministic. Also, it still would impose the temporal framework on God in order to understand the terms “God created”.

Nevertheless, we know that God sees the future and knows what will happen with us. He also knows what we will choose. He knows what is going to be and tells us what we should do when we see those things happening. We know all these by faith. In other words, the concept of God as the omniscient one is given to us by faith. The certainty of the conviction is neither a proposition of reason nor a memory of experience; it is a conviction of faith. How God knows and what His experience of knowledge is like is too lofty a knowledge for man to have. To fully understand the knowledge of God one’s knowledge must be greater than God; this is obviously impossible. Therefore, we come to Him by faith and see only as much as He reveals to us and we have faith in God's revelation.

1. Omniscience doesn’t mean that God experiences knowledge of sin in the same way that the sinner does. The sinner possesses experiential knowledge of sin. But, God doesn’t have experiential knowledge of sin, since God is sinless. Therefore, we are told, “He knew no sin” (2Cor.5:21).
2. Omniscience is not limited only to what God has determined to do, His plan; on the contrary, God knows everything that is, was, and is going to happen (e.g. Dan.11; John 13:38).
3. Omniscience is not something that God acquired when He created the world. God knew everything before the foundation of the world. Note that we have used temporal terms to talk of God here, but we know that God is beyond these categories of talk (Eph.1:4).
4. Omniscience doesn’t mean that God’s actions in the world are determined; nor does it mean that man’s actions are determined. It simply only means that God knows all things without determining human choices. This, however, doesn’t mean that God doesn’t lead and guide people or abandon them to their hardened heart if they reject His guidance. Omniscience, thus, does not contradict human freewill and responsibility.
5. Omniscience of God is the source of prophecy.
6. God knows all things visible and invisible, all thoughts and actions, and nothing is hidden from His eyes, for all creation is bare before Him (Heb.4:13).