In 1 Samuel 2, King Saul is hunting King David. King David is at the city of Keilah, and wonders what to do:

1Sa 23:8  And Saul summoned all the people to war, to go down to Keilah, to besiege David and his men.
1Sa 23:9  David knew that Saul was plotting harm against him. And he said to Abiathar the priest, “Bring the ephod here.”
1Sa 23:10  Then David said, “O LORD, the God of Israel, your servant has surely heard that Saul seeks to come to Keilah, to destroy the city on my account.
1Sa 23:11  Will the men of Keilah surrender me into his hand? Will Saul come down, as your servant has heard? O LORD, the God of Israel, please tell your servant.” And the LORD said, “He will come down.”
1Sa 23:12  Then David said, “Will the men of Keilah surrender me and my men into the hand of Saul?” And the LORD said, “They will surrender you.”

David asks God two things. David asks if Saul is coming to attack him. God says yes. Then David asks if the people will turn him over to Saul. God says yes again. David is asking for insider knowledge from God. David does not know the disposition of the people and relies on God to inform him. The people are probably afraid of Saul (who kills priests for harboring David (1 Sam 22)), and they probably owe their allegiance to the current ruler of Israel and his armies. God sees this and warns David.

Negative theologians seem to take this verse as some sort of prooftext showing that God knows “all possible futures”. This features in the most popular Systematic Theology book sold on Amazon: Wayne Grudem’s Systematic Theology: An Introduction to Biblical Doctrine:

The definition of God’s knowledge given above also specifies that God knows “all things possible.” This is because there are some instances in Scripture where God gives information about events that might happen but that do not actually come to pass. For example, when David was fleeing from Saul he rescued the city of Keilah from the Philistines and then stayed for a time at Keilah. He decided to ask God whether Saul would come to Keilah to attack him and, if Saul came, whether the men of Keilah would surrender him into Saul’s hand. … And the LORD said, “They will surrender you.”

Likewise, other theologians make the same claims. Otherwise scholarly Michael Heiser states:

So in summary, with respect to actual events, God may or may not have predestined them, but he foreknows them all—and even foreknows events that don’t happen. And it is at this point that I am in disagreement with open theists who insist that God doesn’t know human choices ahead of time. That seems incoherent in that, if God foreknows events that don’t happen, why wouldn’t he foreknow what the possible choices were and which choice would be made? How can God foreknow a list of options that will not happen, but be unable to know the thing that does? This makes little sense.

The problem with this is that the prooftext proves too much. It takes a normal everyday occurrence (predicting people’s actions) and ascribes extraordinary conclusions. It is a non-sequitur. There is no link between God’s knowing the strength of people’s allegiances (what they will do when pressed) and knowing “all possible futures”. Probably any insider from the city would know the exact same thing.

In fact, plenty of instances in the Bible (and in modern life) show normal human beings making similar predictions. This is because it is easy for anyone to know what people will do just using common sense and present knowledge. In Genesis 12, Abraham (Abram at the time) predicts what the people of Egypt would do if Sarah (Sarai) did not pretend to be his sister:

Gen 12:11  When he was about to enter Egypt, he said to Sarai his wife, “I know that you are a woman beautiful in appearance,
Gen 12:12  and when the Egyptians see you, they will say, ‘This is his wife.’ Then they will kill me, but they will let you live.
Gen 12:13  Say you are my sister, that it may go well with me because of you, and that my life may be spared for your sake.”

Abraham is not “Omniscient”. Abraham did not know “all possible futures”. This is not a prooftext for a strange conception of Abraham’s knowledge. Instead, Abraham used his present knowledge to extrapolate on the motives of people he had never before met. This was not a hard prediction. Abraham’s suspicions seem to be true, evidenced in Pharaoh’s attempting to capture Sarah against her will.

There is no reason to make more of 1 Samuel 23 than it presents on face value. David is merely requesting that God inform him on the state of Keilah’s allegiances. This is doubly true considering that the same author wrote 1 Samuel 15 in which God regrets His own actions. Grudem seems to be stretching his theology to explain why a God who knows the future would think in conditional terms. This theological stretch just does not fit the entirety of the narrative of 1 and 2 Samuel.