I wish to quote J. Alexander Rutherford on the issue of Abstraction:

I think that neither of these extremes is appropriate. To the contrary, abstraction properly conceived is a necessary tool in coming to true knowledge of God and His created world. If we want to think intelligently in this world, we need to use abstract thought. Yet if we want to think faithfully, we must think abstractly in the biblical sense and not in the sense of non-Christian philosophy. In this first article, I want to look at non-Christian abstraction and its problems. In the next article, we will look at a Biblical view of abstraction.

In non-Christian philosophy, abstract thinking is set in opposition to concrete thinking. Concrete thought is concerned with the particular objects of our experience. It is not interested in knowing what “dogs” are like; it wants to know what Fido is like. Instead of studying anthropology, concrete thought wants to know about John, an individual human.

Abstract thought, in contrast, is concerned with general categories that encompass particular objects. Fido is only of interest to the abstract thinker in as much as he sheds light on “dogs.” John is only important in as much as he reveals something about “humanity.”

For the early Greek Philosophers, abstract knowledge was the only thing that truly qualified as knowledge. For Plato and Aristotle, Fido or the oak tree out your front door do not matter. They are not objects of knowledge. True knowledge is of “dogness” (that essential element that defines a dog) or “treeness.” In this sense of abstract thought, the differentiating features of particular objects or persons (size, height, colour, pattern, behaviour, personality, history) are not objects of knowledge. Instead, abstract thought focuses on the unity of objects; true knowledge is of irreducible essence of a human being, a dog, or a tree. To truly know something is to know the essence, that without which it ceases to be (what is the characteristic that if taken way would disqualify a person from being human or a dog from being a dog?).

Why in the world, you may be asking yourself, would someone define knowledge in this way? Abstraction in this non-Christian sense, if possible, allows humanity to have completely autonomous knowledge of everything. That is, if true knowledge is found in abstracting the irreducible essence of things, it follows that eventually you will arrive at true knowledge of everything. But if true knowledge is of particular objects, we are doomed to know almost nothing!

Think about it. How many objects have you encountered in your life? How many objects are there in the universe? If true knowledge is only of things we experience, we really do not know much at all. Moreover, we do not know how unknown objects might influence the objects we do know! What if there is a being just beyond our experience that interacts constantly with every object of our experience? In this case, we really don’t know the objects of our experience, for we don’t know anything about this essential influence that contributes to their particular existence. To know anything rightly, you must know everything; only by knowing everything can you be confident that your knowledge of any one thing is correct. If to know something you need to know everything, then no human being on their own (apart from revelation from a being who knows everything) can know anything.

https://teleioteti.ca/2018/09/06/abstraction-part1/

I also recommend the second article to this one:

https://teleioteti.ca/2018/09/20/what-is-abstraction-part-2/

To see these points used in an argument between a Christian and non-Christian then I recommend this conversation from Chris Matthew:

http://spirited-tech.com/2019/09/01/the-unity-of-knowledge/