Throwback to 2013, Economist Robert Murphy responds to Open Theist remarks by writing a blog post on omniscience:

==> First of all there are the prophecies, such as God’s promises to Abraham in Genesis and of course the entire Book of Revelation describing the end times. Thus from start to finish, the Bible shows that God has knowledge of exquisite details of the far-distant future. These aren’t generic statements like, “Energy will be conserved in the year 2834.” No, He is giving very specific descriptions of events. How can He do this if He’s not omniscient? It’s as if He’s the Alpha and Omega; oh yes, that’s exactly how He Himself describes it.
==> Job 42:2: “I know that thou canst do every thing, and that no thought can be withholden from thee.”
==> Psalm 44:21: “Shall not God search this out? for he knoweth the secrets of the heart.”
==> Proverbs 15:3: “The eyes of the Lord are in every place, beholding the evil and the good.”
==> Jeremiah 1:5: “Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations.”
==> Luke 12:6-7: “Are not five sparrows sold for two farthings, and not one of them is forgotten before God? But even the very hairs of your head are all numbered. Fear not therefore: ye are of more value than many sparrows.”
==> John 21:17: “He saith unto him the third time, Simon, son of Jonas, lovest thou me? Peter was grieved because he said unto him the third time, Lovest thou me? And he said unto him, Lord, thou knowest all things; thou knowest that I love thee.”
==> Ephesians 1:4-5: “According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love: Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will…”
==> Let me admit that there are certain passages in the Bible where–if you didn’t have the above to go on–you might think that God is fallible. But many of them are of the form of God asking questions. Yet clearly there are cases where He obviously knows the answer. For example, when God asks Cain where Abel is (whom he has murdered) and Cain infamously retorts, “Am I my brother’s keeper?” does anybody really think that in this story, God didn’t know the answer before He asked?

Mr Grey responds:

Second, your argument from Biblical claims also seems a bit shallow, in that every verse cited is a third party making claims about God’s intelligence. God himself does not claim omniscience (though in Is. 55:9 he claims that his thoughts are superior to Man’s), only those writing on his behalf do.
Moreover, these claims are made in foreign languages used over two millenia ago, which may mean that our understanding of what, exactly, is meant by these claims is hampered by translation difficulties. E.g. is the sentiment of “The eyes of the Lord are in every place…” that God is closely monitoring even the deepest reaches of other galaxies for human sin, or that he simply has a pretty good grasp on what people are actually doing on a day-to-day basis? Granted, there really isn’t a practical distinction to be made between either state, but the broader point–God knows if you’re good or evil–is really what we should focus on, not whether this implies God is omniscient. Whether he is or he isn’t, it is sure that he does know whether we obey him or not.
Perhaps it might simply be the case that those who claim God knows everything are akin to the little children who go around bragging that their daddies can do anything. In the case of the latter, it isn’t really true that a human dad is so awesome that he can do literally everything in the universe, but four-year-olds are generally sincere in that particular belief. Likewise, it may simply be the case that God’s spokesmen are so in awe of God’s superiority that they might be exaggerating a little bit.