In a podcast (transcript here), William Lane Craig says the following:
Dr. Craig: . . . If God is in time then there are tensed truths. That is to say, there are propositions which have verbs in them that are in the past, present, future, and other tenses. And therefore these propositions change their truth values as time goes on. For example, it was once true that Columbus will discover the New World. A little later it was then true that Columbus is discovering the New World, and as time passed it became true and is now true that Columbus discovered the New World—past tense. So what this means is that if there are these objectively tensed truths that change their truth values from going from false to true, then God, in virtue of being omniscient and knowing all truths, will come to acquire new beliefs—he will learn new truths, namely, as the proposition “Columbus discovered America” switches from having the value false to having the value true, this now will come to be believed and hence known by God. And so a God who is in time will have a knowledge that is constantly changing, he will have a knowledge that is constantly growing, we could say learning new things, as new propositions become true. So far from entailing his non-omniscience, God’s omniscience would actually entail that his knowledge will be changing and constantly being added to as new truths come into being.
[Interviewer]: Some people may be thinking that you’re saying that God didn’t know that Columbus, for sure, would discover America and he came to know that when he goes, “Oh, look!”
Dr. Craig: No, no, that’s not what I’m saying. I’m saying that before the event God knew the future tensed proposition “Columbus will discover America” but he didn’t know the proposition “Columbus discovered America” because that was false at that time. That was false at that time. So that proposition switches truth value once Columbus has made his discovery—it goes from being false to being true, and since God is omniscient (and omniscient means knowing and believing only and all truths) God must come to believe that proposition now. And he will no longer believe the proposition “Columbus will discover America” because that proposition has now become false. It used to be true but it isn’t any longer, so God won’t believe it anymore.
So, you see, God does learn new tensed truths all the time, because he is omniscient.
Craig and the interviewer go on to claim that “people need to get past third grade Sunday school theology.” apparently claiming that the view that disagrees with them is elementary and naive.
Here we must disagree with Craig, for his mistake leads to a very serious error. Craig makes a mistake by not being precise with his truth statements. Using his example, Columbus discovered the new world in 1492. In 1491, the statement “Columbus discovered the new world” (past tense) is false, while in 1493 the statement would be true. However, he is incorrect in saying that the statement made in 1491 changes from false to true, for it is true for all people in all time that the statement made in 1491 “Columbus discovered the new world” is false. The statement was false in 1491 because it was made in 1491, but it is still false for all times that the statement “Columbus discovered the new world” was false in 1491. Likewise, it is true for all people and all times that in 1493 “Columbus discovered the new world” is true. The point Craig was making is that the truth statement changed, when in fact it was merely an imprecise example statement. Using the tensed statement “Columbus discovered the new world” is only meaningful made in time, and when moved to another time either becomes a different statement or becomes imprecise and unknowable. More correctly, we would have to say something like “As of today, Columbus discovered the new world.” We would then have to ask “when is today?” and we would know whether it was true or false. Regardless of when “today” was, the statement would be either true or false for all times. Making a statement with tensed verb apart from a point in time is merely an imprecise example. Again, apart from a time reference, a past tense statement is not meaningful. “In 1492, Columbus discovered the new world” is a past tense statement with a time referent, which has meaning,
This imprecise view of truth leads Craig to hold to the position that God can be omniscient and still learning. To his credit, he does hold that God is not surprised by things, so in that sense Craig holds that God knows all things. However, this is a tortured view of omniscience, saying that God is constantly learning new truths but always knowing all truths, as Craig says in two sentences above.
Rather, holding that God truly does know all truths and does not learn is not a “third grade Sunday school theology.” These statements are unfair, unjustified, and uncalled for. In but one example, the great theologian Charles Hodge says of God’s knowledge:
This distinction between the possible and actual, is the foundation of the distinction between the knowledge of simple intelligence and the knowledge of vision. The former is founded on God’s power, and the latter upon his will. This only means that, in virtue of his omniscient intelligence, He knows whatever infinite power can effect; and that from the consciousness of his own purposes, He knows what He has determined to effect or to permit to occur. (ST, 1.398)
Thus all of God’s knowledge is included in what He has determined to effect or permit to occur, which scripture tells us He knew from the beginning, prior to any earthly human action. If we include the possible and the actual in God’s knowledge, we have included all states of affairs, therefore God is omniscient in the fullest sense of the word. If God’s knowledge changes in any way, it must result in God being limited in some sense, whether it be knowledge or power. This is a serious error.