Please, no "God is love" stuff. You have no idea what that phrase has put us through. Ahem Lukvance. Cough cough.
An example of defining something by properties would be like me defining the color blue:
Blue is the light in the visible spectrum of electromagnetic radiation (energy) that has a wavelength of 450 to 495 nanometers (thanks wikipedia). You can even try to define blue as matter, provided you have enough knowledge in physics.
Furthermore I can say that it has a frequency of 606 to 668 tera hz. I could go on to explain that the photons that make up blue light have a certain amount of energy, in joules, but you get the point.
I am letting you know exactly what I mean when I say "blue"; it's a specific kind of light that has unique characteristics that other kinds of light do not.
I would like to ask you to give a more detailed definition of god (lowercase), keeping in mind how I defined "blue". Perhaps let me know the composition of god, is he/she/it matter? Energy? Force? Concept?
Existence. if something exists, it has a location, AND a time, correct?
For instance, if I say "my laptop exists", I am more specifically saying that it has a physical location (in this case atop my desk), AND a specific time frame for itself. Meaning that if I take my laptop elsewhere, it would still have a location, and time frame for when it was at that location.
That is how you can prove something exists in this universe; it has a location and time. it fits well with our understanding of time and space.
Emotions exist. Why? They are what we call a chemical process in the brain (location) that occurs at a certain time. They have a time and location.
Every single thing in existence can be explained this way. People, bullets, etc.
Supernatural. Is the entire universe not natural? It is. Nature is literally everything in the universe; matter, energy, aliens, etc.
Therefore, supernatural would have to be somehow "not in the universe."
How can you demonstrate that? How can you demonstrate something supernatural? When we observe something, anything; it's because that something exists within the universe, and we have experienced that phenomenon through nature (whether that be through sound, vision, touch, etc).
Going back to existence.
The problem with gods is that... where (location) and when (time) are they? (I'll leave it up to you to define WHAT they are in the first place).