“There is no path to nirvana;
nirvana is the path.”
~Thich Nhat Hanh
Secular Enlightenment is real; it is a perspective of awareness and can be explained by neurological processes. It is the process of flowing, awakened experience; it is a path of living in present time beyond the mind’s processed reality. Awakening is the shift to that perspective of direct and objective experience.
It is difficult to precisely correlate the historical terms with present day understanding of neurological function. Monks who lived even centuries ago had no way to study the neurological basis of the mind except by direct experience.
Modern neuroscience, however, confirms that our typical general experience is a conceptual reality. It is produced in the middle prefrontal cortex by the splicing of bits of perceptual data with images, stories, and memories stored in the visual cortex, temporal lobe, amygdala, and hippocampus. This simulated reality is biased towards creating a self identification that favors input and memories that reinforce its own existence. The virtual self is then enabled to engage in the dramas, traumas, and joys of life - some more real than others, many completely fabricated. Attachments to material world objects, beliefs in a conceptual self, are attachments to systems of conceptual reality - the illusion.
Enlightenment, as a term, is useful to sanctify spiritual attainment to seduce the egoic mind to unwittingly release in the pursuit of a "better" experience. As such, the term functions as an egoic trap that can lead ultimately to the submission of ego in favor of direct awareness.
One might reasonably assert that there is no enlightenment by use of clever contextual obscuration (Zen). It can also be denied as a mystical transcendence (most religions). However, the experience of enlightenment is a fundamental state of awareness explicable by science; one typically awakens to it when cognitive dissonance subverts conceptual reality. Its subtle innate nature is so obvious that it is easy to miss.