Classical theism tends to start from the idea of God as an absolute and perfect being, and secondly explains how this abstract idea becomes personal in the God of the Scriptures. First, what is God? And second, who is God?
All human beings have some concept of divinity. "For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen. (Romans 1:20, New American Standard Bible). Consequently, when someone searches for the existence of God he already has some concept of what kind of existence he is looking for.
The abstract concept of divine nature or divine essence is crucial for classical theism. God is by definition the most complete and perfect being thinkable. He is essentially distinct from his finite and dependent creatures.
Whatever one might believe about classical theism or open theism, it is good that the teaching of God is again in the forefront. Open theism challenges many traditional ideas and forces us to a deeper understanding of the biblical text. Indeed God is personal and relational. The abstractions of classical theology end up with a God of the philosophers and not the God of Abraham, Isaac, and Jacob.
However there are some serious flaws in the open theism model, and we need not leave the classical model to perceive God as a loving person. I mention six issues that for me personally are decisive to finally refute open theism.