It's difficult to explain because God is impossible to define, so it's entirely possible you believe what I believe as well but we're expressing it in a different way.
This is nonsense. If God is impossible to define, then how can you be a Christian?
Defining God
To begin, we must recognize the limitations of language. Meaning arises not from the words themselves but from a shared framework of experiences, concepts, or references between the speaker and listener. Without this common ground, misunderstanding is inevitable. For example, what modern science defines as “force” might be more easily understood by an ancient mind as “spirit”, reflecting their fundamentally different worldview.
With this in mind, it might be useful to begin our attempt to define God using John's definition:
John 1:1 NRSVUE
In the beginning was the Word, and the Word was with God, and the Word was God.
The "Word" in this instance is logos, the root word of logic. This may be a good place to start since (a) it is Biblical, and (b) we generally subscribe to logic as a useful parameter.
The Greeks had three transcendentals: truth, goodness and beauty. The word transcendental is also useful in this context, as it implies a metaphysical, if not supernatural, reality. I'm not arguing that such a reality exists in the sense that I might argue that God exists. I'm just asking you to note the word. I'll be coming back to it.
Science is our bastion of truth. Indeed, the word is almost synonymous with truth. Even if we don't understand it, nor seen it with our own eyes, the fact that scientists believe it is often sufficient evidence for us.
Fundamentally, science is a human construct, our interpretation of the data we have based on our laws of logic. At the same time, science is the study of nature. Thus, science discovers laws of nature even though the mathematics behind it are our invention.
So, can we agree on these:
• the wonders of science are in fact the wonders of nature
• nature, as presented by science, is entirely logical (i.e mathematical) and yet paradoxical (e.g. glass is not just solid, but retains liquid properties, irrational numbers like pi and e are common in nature, energy can exist without mass)
• the laws of nature are complex but often reduces to elegant and simple formulae (which is often used as a measure of good science)
• despite so many years and so much effort to understand nature, it continues to elude us (we constantly feel like we're on earth looking at the stars far, far away)
When this last step occurs, there's a sense of transcendence. It's an exhilarating feeling but the opposite of the eureka feeling. Instead of feeling that you've solved a particularly difficult problem, you're amazed at how much lies before you. It's not just a sense of being overwhelmed by the vastness before you but also the sense that it's entirely logical but way beyond you. You are excited because you have the tools to explore this reality, and there's so much to discover and yet, it seems inexhaustible.
I'm not saying that this proves that God exists. I cannot prove that God exists because of the differences in our frameworks which I have pointed out above. This is just the first step towards defining God. I'm just establishing common ground. If we can agree on this, we can move on to the next step.