It is striking how long people can spend - either speaking or writing - expounding (in multiple ways, from many angles, with countless examples) the metaphysical view that ultimately everything is one.
Since Plato - at least - this has been a major theme of philosophy - Eastern and, more recently, Western. The idea that variety is illusion, that reality is one, eternal, changeless; that thinking is the enemy; and that we need more than anything to stop thinking; to just be, and then to become assimilated to the one-ness in a state of no suffering (at the least - and perhaps, at best, timeless bliss...).
If one's experience of this mortal life is primarily one of suffering, once one regards this mortal life as the only life - then this is a logical solution. If suffering is the problem, then not-suffering (or bliss) is the answer. It then becomes a question of how to achieve not-thinking, non-attachment and not-suffering...
This leads to those types of meditation that focus on attaining such a state during this mortal life; the types of meditation that aim at not-thinking; at simply being; at sublime indifference to the world, change and all that is distressing.
I personally find it hard to distinguish this type of meditation from deep sleep - when temporary - or death (understood as annihilation of the self) - when aimed at as a permanent state. Drugs that achieve an obliterative intoxication seem a quicker and more reliable solution than decades of meditative discipline...
Certainly this aimed-at one-ness is not a human state; it is precisely the removal of human-ness from a person.
It seems to me an acknowledgement that mortal human life is a mistake; therefore the solution is to abolish it.
Such a view can't really be fitted into a Christianity based on God as creator and loving parent; since such a God would not have made such an egregious error as to compel his children all to live-out a futile and miserable mortal life, the goal of which would be its own negation.
All of which shows how important it is to be clear about one's basic concept of life. We can't know what is best for mortal life until we know the place and role of mortal life - whether there is a life before and/ or after mortal life; and what are the nature of such pre- and post-mortal states.
Lacking any such metaphysical set-up, talking (whether at endless length or briefly) about the purpose or meaning of a person's life... is idle, or indeed worse than idle: malign.