No Why, Dude!

First we have to decide whether or not life and even existence itself are absurd.

Good point. If existence is absurd, then some form of applied acosmism seems the way to go, e.g., Vedanta, Buddhism, or neo-Platonism:

Acosmism is a philosophical and theological view that denies the reality of the universe, seeing it as illusory or a non-essential part of a higher, ultimate reality It posits that the physical universe and all finite objects and events within it do not have a separate or ultimate reality of their own. 

In essence, acosmism is a belief that the world we perceive with our senses is a sort of cosmic illusion or a manifestation that obscures a deeper, singular truth. 

So, you don't really exist, therefore it's best for you to realize this in your bones. Thus the "applied" part, i.e., systematic and radical detachment from, and transcendence of, the illusory ego. 

By whom?

Details. 

The concept of Maya in the non-dual Advaita Vedanta school of Hinduism is a form of acosmism. Maya means "illusion" or "appearances," and it refers to the perceived world, which is considered real in an empirical sense but not in a metaphysical or spiritual one. Liberation is achieved by realizing that the individual self is one with the ultimate reality (Brahman).

You will notice that this approach doesn't touch on the question of Why we are here. Rather, there is no Why. As proclaimed in the sacred Deteriorata,

You are a fluke of the universe.
You have no right to be here.
And whether you can hear it or not,
The universe is laughing behind your back....

With all its hopes, dreams, promises, and urban renewal,
The world continues to deteriorate.
Give up!

It reminds me of Gary Shandling, who practiced Buddhist meditation for 35 years, until his mind was "pretty empty, pretty blank." At which point "there was no one left to blame." 

But it's not only Eastern philosophies that advocate laying down all thought and surrendering to the Void: "In Western philosophy, thinkers like Spinoza, Johann Gottlieb Fichte, and Hegel have been described as acosmists."

Note that acosmic philosophies don't shy away from the absurdity of the universe, rather, emphasize it. One can realize Brahman -- the ultimate reality, source, and ground of being. But why is there an existence separate from Brahman to begin with? No reason. Whatever this world is, it's just an unintended side effect of something resembling Schopenhauer's pure will.

Yes, there is a strong and intentional parallel between Schopenhauer's philosophy and non-dual Vedanta. Schopenhauer himself was one of the first Western philosophers to extensively study and integrate Eastern thought, particularly the Upanishads (the core texts of Vedanta), into his work. 

The Will is the true, underlying reality of everything. It is a singular, blind, irrational, and aimless force that drives everything in the universe, from the gravitational pull of planets to the instinctual desires of a human. It is not a conscious decision-making process but a ceaseless striving, a blind impulse that is the source of all desire and therefore, all suffering. The phenomenal world of "representation" is simply a manifestation or "objectification" of this underlying, irrational Will.

So, the point is that there is no point. Which the Bible doesn't deny, in that the world can at times appear rather beside the point, cf. Ecclesiastes:

Yes, the book of Ecclesiastes is famous for its exploration of the futility of human existence. The central theme is encapsulated in its very first lines: "Meaningless! Meaningless!" says the Teacher. "Utterly meaningless! Everything is meaningless." 

This word, "meaningless," is a translation of the Hebrew term hevel, which literally means "breath," "vapor," or "smoke." This imagery suggests that life is fleeting, elusive, and ultimately without substance when viewed from a purely earthly perspective. 

So, even if there is a God, he's just blowing smoke? 

The author tests various paths to find meaning in life, only to conclude that they are all a "chasing after the wind," and that everything in the natural world is cyclical and unchanging, from the sun rising and setting to the rivers flowing into the sea. 

He contrasts this with the brief, fleeting nature of human life: "What has been will be again, what has been done will be done again; there is nothing new under the sun." The Teacher experiments with pleasure, wealth, wisdom, and hard work, but finds no lasting satisfaction in any of them.

Not unlike the Buddha, who came to the same conclusion. However, while Ecclesiastes 

is deeply pessimistic about life "under the sun," its ultimate purpose is not to promote despair. Instead, it serves as a powerful argument that true meaning cannot be found in the material world. The book's final conclusion points to a different path: "Fear God and keep his commandments, for this is the whole duty of man."

In this way, Ecclesiastes serves as a philosophical and theological journey that strips away all false sources of meaning to reveal that a purposeful life is one lived in relationship with God. 

So, the two approaches (Eastern & Western) look at the same set of existential facts in order to reach the same sobering conclusion about the futility of existence, at which point there is a fork in the vertical road, one path leading to God, the other to... 

That's one of the questions before the house, for if there is a convergence between Vedanta and Christianity, it would have to be on the mystical-experiential plane: in other words, is the realization of Brahman (or Nirvana or Moksha) just another name for the realization of, or union with, God?

It reminds me of something Schuon said about the supposed a-theism of Buddhism: that they have the thing, just not the name, the thing being the experience. 

Which is not too far from certain Christian mystics such as Meister Eckhart. Or think of someone as mainstream as Thomas Aquinas, who underwent an earth-shattering mystical experience that rendered his life's work "so much straw." And if his luminous corpus may be reduced to a pile of horse food, what does this say about the restavus? 

Not even straw?

Yes, one thinks of the other end of the horse.

Still, in the Christian vision there is a Why: 

That is an insightful observation that gets to the heart of a major difference between these two profound traditions. While both Christianity and Advaita Vedanta offer a path to a kind of mystical union, their core cosmologies -- particularly regarding the purpose of existence -- are fundamentally different. 

The Christian worldview posits that the world was created for a specific purpose: as an act of divine love and for the glory of God. Humans, in particular, were created in God's image to have a personal relationship with Him and to share in His goodness.

Thus, mystical union in Christianity is a relationship of participation, not absorption. The goal is for the human person to become one with God in love and will, but without losing their individual identity. It is a "union of wills," where the believer's will aligns perfectly with God's. The soul, while transformed and divinized, remains a distinct entity in a loving communion with its Creator.

Is it conceivable that in Christianity there a Beyond that is beyond even this? Opinions diverge, and ultimately go to the question of whether there is something "beyond God."

How could that be?

Well, it is certainly implied in the metaphysics of Eckhart. To back up a bit, Schuon posits a distinction in divinas between Being and Beyond-Being. As a consequence, God himself -- the personal creator God -- is situated on the being side of the divide. In short, there is a God beyond God.

Is that allowed?

Eh, I don't know, but you can't argue with experience. Or, if we accept Schuon's framework, we do have a context in which to situate some of Eckhart's more controversial, puzzling, and paradoxical claims, which are many. A sampling:

God is a being beyond all being; God is a beingless being.

God acts but the Godhead does not act. The mystery of the darkness of the eternal Godhead is unknown and was never known and never will be known.  

God is a being beyond being and a nothingness beyond being. 

I pray to God to rid me of God. The highest and loftiest thing that one can let go of is to let go of God for the sake of God.

He also speaks of a Nothingness out of which God is born, but I wonder if the Trinity can be tweaked in such a way that the Logos-Son is engendered from the limitless source and ground symbolized by the Father? Except to say that these two poles represent an eternally dynamic complementarity, from which a number of entailments follow, but that's more than enough horse food for unknowing for one post...