The decrease in the birthrate produced an older population that had less ability to defend itself and less will to do so, making the nation more vulnerable to its enemies. Finally, unbelief in God became more complete, parental authority diminished, and ethical and moral principles disappeared, affecting the economy and government. Thus, by internal weakness and fragmentation the societies came apart. There was no way to save them except by a dictator who arose from within or by barbarians who invaded from without. Although this is an ancient pattern of decline found in Greece and Rome, it is relevant today.
Families are the foundation of a nation.
When the family crumbles, the nation falls because nations are built upon family units. They are the true driving social force. A nation will not be strong unless the family is strong. That was true in the ancient world and it is true today. There are many factors in the decline of a nation.