The historian Gibbon concluded that there were five reasons for
the decline and fall of Rome. Gibbon was not a Christian, but here
is why he says Rome fell:

1.) The undermining of the dignity and sanctity of the home,
which is the basis of human society.

2.) Higher and higher taxes; the spending of public money for
free bread and circuses for the populace.

3.) The mad craze for pleasure; sports becoming every year more exciting, more brutal, more immoral.

4.) The building of great armaments when the great enemy was
within; the decay of individual responsibility.

5.) The decay of religion, fading into mere form, losing touch with
life, losing power to guide the people.
From Thru The Bible Vol III on Zephaniah by Vernon McGee (1904-1988)

“…He hands nations over to him and subdues kings before him. He turns them to dust with His sword, to windblown chaff with his bow. He pursues them and moves on unscathed, by a path his feet have not traveled before. Who has done this and carried it through, calling forth the generations from the beginning?

I, the Lord – with the first of them and with the last – I am he.”     Isaiah 41: 2b-4