I was watching the above video in which John Butler is asked whether Enlightenment is something achieved immediately and effortlessly (or not at all); or whether it is a matter of many years of regular and strenuous discipline? And whether there is one true path to 'the peak of the mountain', or many routes?
(One true religion only; or instead that all religions are one ultimately?)
This made me think about how I might answer this question...
I would first have to say that this question presupposes that a solid, 'permanent' state of Enlightenment is (or should be) the aim of life; whereas I would emphasise that mortal life is not about achieving a state of Enlightenment. Instead the purpose is about learning from the experiences of mortal life, with learned-lessons redeemed after death in resurrected eternal life.
What people term Enlightenment is truly therefore the (temporary) feeling we get when we have learned something important. It could be regarded as a sign of such learning. But it is not meant to be a continuous and permanent state. When we have had one Enlightenment, have learned one particular lesson - then we are meant to go on to learning more, and further, lessons; and maybe have further Enlightenment experiences.
I would therefore suggest that neither of the suggested possibilities of immediate/ total or long-term/ incremental Enlightenment are correct; because this mortal life is not the end. For Christians, this mortal life between conception and death is vitally important - yet ultimately it looks towards the life to come. The proper, ideal perspective for regarding our mortal life is therefore eternity.
In a sense it is obvious that all lives (no matter how Enlightened) will end in death; and that corruption, decay, disease and degeneration are all intrinsic to this 'entropic' world.
Therefore, it is a plain error to think in terms of Enlightenment - at least it is for a Christian. For other religions, it may be different - for example, Enlightenment may be what is required to escape the endless wheel of reincarnation... It may be that Enlightenment allows someone to die finally.
So - all religions are not one; nor do all religions lead to the same destination. We either follow Jesus through death to resurrection - or we don't. (There are probably several or many other possibilities; including Hell.)
But for a Christian; I think Enlightenment means something like an insight; properly speaking, a valid and significant insight of permanent relevance to life everlasting in Heaven.