Secularism is another offspring (and a key practical component) of atheism. In practice, it means separation of the society, government (state), society and nation from the Church (first and foremost, the Christian Church).
Like atheism in general, secularism isolate individuals, organizations (businesses, government entities, non-profits, etc.) and entities (villages, cities, districts, regions, states, provinces, nations/countries and unions) from the ultimate source of Divine Grace.
Happiness is ultimately determined by the amount of Divine Grace in a human soul, organization or entity; consequently, by isolating the Western civilization from the ultimate source of Divine Grace, liberals make all of the above deeply unhappy.
Even worse, by isolating both individual and collective souls (egregores of organizations and entities) from the source of Divine Grace, liberalism creates an enormous void inside individual and collective souls.
Without protection from God, this void is inevitably occupied by demons of eight deadly sins – pride, lust, greed, gluttony, envy, wrath, sloth and fear – and by legions of other very nasty demons.
These demons (1) make individuals, entities and organizations deeply unhappy in this life; (2) drag human souls to Hell in the afterlife – for eternity; (3) drive individuals, entities and organizations genuinely insane; and (4) create chaos in individual lives, organizations, entities, nations, countries, human society and human civilization.
And individual and collective chaos and insanity inevitably destroy our civilization as we know it and transform our world into a very real Hell on Earth.