Usually, when two theories are advanced to explain the same phenomenon, both theories miss a root cause common to both.
In this case, the root cause of the decline of the West is Protestantism. Its insistence of Bible alone sufficient for individual understanding of Christianity disrupted the continuity of Christian faith from the Fathers of the Church and gave rise to a self-contained skeptic who believes that because he can read he has no need for the Church, and because he can figure out science he has no need of God.
Its idea that faith is separate from good works, and that predestination operates without regard of good works based on declarative faith alone has created a man without an obligation beyond an economic debt. Child rearing then ceased to be a work of obedience to the first commandment given man, and became a matter of economic expediency; marriage became a contract voidable upon mutual consent.
Both theories have a common root.
Ignore the sins behind the curtain.
You surely remember them!
They were Counter Reformed away after the SINs of the CHURCH caused certain brave people to PROTEST them.
And yet it's Catholics (alongside liberal Protestants) who are Biblical skeptics and worshipers of "science." Visit any "traditional" Catholic forums and even there any insistence that Revelation trumps "science" is met with accusations of "Protestantism."
Its idea that faith is separate from good works, and that predestination operates without regard of good works based on declarative faith alone has created a man without an obligation beyond an economic debt. Child rearing then ceased to be a work of obedience to the first commandment given man, and became a matter of economic expediency; marriage became a contract voidable upon mutual consent.
Protestant antinomianism is a logical inference from the antinomianism of the "new testament" and the church fathers. To condemn antinomianism while simultaneously proclaiming that "the law" is a "curse" or a "pedagogue" that has been "done away with" is the rankest hypocrisy.
Ultimately it is chrstianity's rejection of the Torah (and the Noachide Laws) that leads inexorably to antinomianism. Although Protestantism's assertion that the Biblical ceremonial system was abolished and replaced with nothing is far more intellectually consistent than the Catholic/Orthodox position that the Biblical ceremonial system was abolished (and is now forbidden) and replaced by a new, "mandatory" post-Biblical one.