From the article Why I Reject Open Theism:
Open theism is the belief that God does not know the future because he has given man the freedom to choose. One web site gave the following definition: Though omniscient, God does not know what we will freely do in the future.
This is not true, for the Bible is full of references of God declaring future events long before they happened and the outcome of the choices made by individuals long before those individuals were born.
The above is an example of the shoddy debate framing by modern Open Theists and their critics. Sloppy definitions of words are used, and this creates shifting definitions within statements.
Most normal people are said to “know” the future in some sense. I know Walmart will be open if I go right now, and they will accept my money in exchange for candy. This is a certainty. No one would say I do not “know” this will happen.
Queue the theologians. They tend to speak in very different ways. Although they use the same language, it is given a new definition to meet philosophical objectives. In Classical Theism, God’s know is object-based. The knowledge is of real things to be known. God cannot have non-object based knowledge, like experiential knowledge. God is only called omniscient if He has all knowledge, the knowledge cannot change, God’s total knowledge cannot be modified, and God does not receive His knowledge from outside sources (the knowledge is identical to His essence). This is a Platonic idea of knowledge and has nothing to do with the Bible.
So when Open Theists frame the debate in the same idiosyncratic and non-intuitive terms that their critics use, this creates scenarios where these definitions are imposed onto the Bible. Instead of God knowing what will happen in the way that I know Walmart would facilitate my purchase, instead they claim that when the Bible talks about God’s knowledge of the future it meets and entirely different standard. This standard is modern, and alien to the Bible. It leads to people like the author of the quoted article, rejecting Open Theism on grounds he honestly believes are Biblical.