The notion of upward linear progress is nonsense, as I have noted previously. But the proponents of this vision are not only wrong – they exhibit their ignorance of scientific knowledge.
Tides do not continuously rise; they rise and fall. (If tides did continuously rise, everyone would eventually drown. But I digress.) If they truly believe that there is a “tide of history,” they should know that the “high tide” of equality and tolerance for all will recede. So the “tide of history,” as it is currently understood, does not exist.
But in a sense, the holders of this worldview are correct – there is indeed a “tide of history.” However, the tide of history is cyclical, not linear, and reflects change in the human moral order.
The “tide of history” is the story of the rise and fall of human civilizations. Nations rise and fall, empires wax and wane, dynasties form and collapse, based on their fidelity to the unchanging natural law of God.
The Church alone stands timeless, immune to the ebbs and flows of history. Her fidelity to the unchanging teachings of Christ stands forever.