I point to your phrase - "however one would choose to define that." That really is what it boils down to. You are pointing to a behavior and assuming a cause which you cannot define or identify and call it spirituality. I concede the behavior, but that does not mean your assumption as to cause has any validity at all.
Understand I am not saying it does not exist. I personally believe it does, but my belief does not constitute proof nor does it make me right. All of the behavior can be explained rationally with no contact with anything greater than ourselves (that is not how I view spirituality btw, but that is another discussion).
Now, I agree a fact is a fact. That which is... is. However, what we are talking about is calling something a fact. A fact may be a fact, but simply calling something a fact does not make it one. A fact is a fact because it is, not because you believe it to be.
Yet another profound post of pontification without one single instance of peer-reviewed scientific evidence to support it.
All of the behavior can be explained rationally with no contact with anything greater than ourselves
I disagree. The behavior of human spirituality. It can't be rationally explained without something greater than self. If it was figment of imagination, delusion, fake... it would have died out a long time ago as an attribute, it wouldn't have become our most defining attribute as a species, and the basis for all we've become. Now, there are a lot of irrational explanations, like the irrational notion that humans created spirituality to console fears of death, which other species simply don't exhibit. Or the irrational notion that man invented spirituality to explain the unexplained, before going on to invent math, science, physics, psychology, philosophy, quantum physics, etc., to rationally explain the unexplained.
You are pointing to a behavior and assuming a cause which you cannot define or identify and call it spirituality.
But it has been defined, you are asking for more specific definition. It's identified! Do you have some misunderstanding of what we're talking about? Are you having a personal problem comprehending "spiritual" or what? The word "spirituality" is used to describe a real human attribute that does indeed exist. If you need proof that people practice spirituality, turn on the TV Sunday morning and flip through the channels, you'll see humans practicing the attribute. Look for buildings with a funny looking pointy thing on top, usually adorned by a cross, (it's called a steeple.) In those buildings, you will find human beings practicing spirituality. So for you to continue arguing there is no proof of spirituality, is simply foolish. What you seem to have done here, is confuse "spirituality" with "spiritual nature" and you are arguing there is no proof of spiritual nature, not the attribute of spirituality.
However, you are wrong about that as well, there is plenty of proof that spiritual nature exists, it's just not physical proof. If it were physical proof, the spiritual would be physical in nature. Now, you ask, how do we evaluate spiritual evidence? Well, the same way we evaluate physical evidence, through observation. One of your 'fellow travelers' said it best:
"...it most certainly does enable one to reach a sense of "inner peace" and a "feeling of connectivity." So we see humans practicing spirituality, and it seems they gain some benefit from this, a sense of inner peace and connectivity. We have the testimony from billions of humans who practiced spirituality, attesting to the enormous benefits they gained.
Of course, you'll say this requires faith, and you'd rather believe in science. But science is dependent upon your faith as well. You need faith in your theories, faith that the physical principles of the universe will remain unchanged, faith that evidence is proof. If you applied the same criteria to spiritual nature, you'd believe in it as well. The reason you don't or can't, is because spiritual nature is not physical nature, and you only acknowledge physical nature.... in spite of all the evidence that spiritual nature exists.