What Is Spiritual Enlightenment or Spiritual Awakening?

http://endless-satsang.com/spiritual-enlightenment-spiritual-awakening.htm

"how does one explain the birth of unconditional or divine love?"

That is the result of a purposeful awakening by the Divine, and taken to the pinnacle of human enlightenment capability.

"One such definition for spiritual enlightenment is the complete dissolution of one's identity as a separate self with no trace of the egoic mind remaining. This sets the bar very high and means that very few people qualify as enlightened."

In human terms, the ultimate.. It takes lifetimes to reach it, which is why it is so elusive. Everybody is on a path to that, whether they know it or not (or should I say, their soul is), so I'd say everybody is enlightened to some 'stage', but the path is extremely long (for most).
The negative of this... Anybody who separates Humanity into divisions of what I've heard termed as "Spiritual abundance", needs to take a serious look at their own thoughts. There is no such thing.