Who knows? This much I do know. Virtually every religious tradition has coined words and concepts to tell the story of their experience of transcendence. But, no one word or concept could ever fully capture whatever it is that happens in the human experience, the consequence of which leaves one radically and forever different. Where the world comes alive to you; where all humans, indeed all sentient beings, are suddenly sacred to you, regardless of their color, nationality, or religion; where you know and feel your own infinite worthiness; where there is profound joy, sometimes expressed as laughter, but always somewhere in the background of consciousness, a feeling of utter satisfaction with who you are and the way things are.
I love the way the Buddha himself (whose name, coincidentally means, "Awakened One") expressed what I am saying when he was once purportedly asked, "What do you and your disciples do?"
He answered, "We sit; we walk; we eat."
The inquirer was perplexed. "But," he objected, "doesn't everybody do sit, walk, and eat? What's so different about that?"
"Yes," replied the Buddha. "It is true we all do this. But, when we sit, we know we are sitting; when we walk, we know we are walking; when we eat, we know we are eating."
Isn't this what it means to be awake? To be enlightened? To be born again? To be saved? It does for me. And, I think it does for most people who have experienced that which is Inexpressible, who know what is unknowable, who live and walk with an awareness there is Something, maybe even Someone, who, as I prefer to call her, is God - that One who is nearer than the air we breathe. Who knows? Perhaps she IS the air we breathe, just as she is part and parcel to the other "ten thousand things" Lao Tzu called them.
All I know is about as much as the man born blind to whom Jesus gave sight one unsuspecting day (John 9). When the authenticators of proper orthodoxy questioned the transformed man about what it was that had happened to him, the best he could say was, "I was blind, now I see."
For those who see, that explanation is enough. For those who don't, it's never enough.