The saeculum is the world in its temporal span. As such, it is simply God's good creation in its providential unfolding. However, "secularization" is the ideological operation by which we refuse to acknowledge that the saeculum utterly depends on the goodness and wisdom of God. Secularism, therefore, is the bending of the world and history back on itself; it is the macrocosmic and world-historical parallel to the curving back on self (incurvatus in se) that Saint Augustine identifies as the essence of sinful subjectivity.
In either case, what happens is that we fail to be grateful for the world, for the mystery of being. And without gratitude, we waste away: wonder dries up; our heart shrivels; the natural bases for faith, hope, love collapse.
And that's what we hear about in the first Mass reading yesterday: "Thus says the LORD: cursed is the man who trusts in human beings, who seeks his strength in flesh, whose heart turns away from the LORD. He is like a barren bush in the desert that enjoys no change of season, but stands in a lava waste, a salt and empty earth" (Jeremiah 17:5-6).
A closed world order means contracting the horizon of human possibility, reducing it to the exercise of power. It results in the barbaric zero-sum game we call "looking after myself."
Only if we recognize the reality of providence can we live differently, in a non-grasping way. By faith in invisible goodness.
The great political philosopher Eric Voegelin speaks of any true progress in history as the flux of "being" in luminous movement towards the divine Beyond.
Or, more simply, our pious gratitude for existence allows the world to light up for us as iconic of the invisible--of infinite truth, goodness, and beauty. Without the reality of transcendence, we cannot transcend the self. And it is only in the process of self-transcendence (which also happens, indeed happens most profoundly, in suffering), that a human is alive in the relevant sense, living by the infinite knowing and loving that is the Spirit of God:
"Blessed is the man who trusts in the LORD, whose hope is the LORD. He is like a tree planted beside the waters that stretches out its roots to the stream: it fears not the heat when it comes, its leaves stay green; in the year of drought it shows no distress, but still bears fruit" (Jeremiah 17:7-8).
Of course, this sends us back to the first psalm, and its description of the two ways: the way of life, a seeking after God's wise and loving disposition of the world and history, versus the way of death, a denial that our estimation of what's worthwhile must yield to a higher judgment.
Which leads to the Gospel reading, in which Jesus speaks to the Pharisees about Lazarus and the rich man... Beyond brutal insouciance concerning our suffering neighbor and our sense of being entitled to an undisturbed zone of comfort, there are encompassing claims of mercy that expose and repay the mercilessness of our hardheartedness (our secularism). The divine Beyond disrupts and upends our secularized arrangements.
Jesus is the visibility of transcendence. He is the Word of Life. His Resurrection is the vindication of love--the vindication of radical solidarity and of every victim of the world system who got staked on there being something more than the will to power and the private judgment of man.
The way of life is the way of the open heart: the way of humility, solidarity, gratitude; the way of joy and hope; the way of faith and love.