As the Roman Empire finished its religious transformation in 406 AD, Alaric's advance and barbarian invasions exposed "Christian" Rome's ultimate failure—proving the transformation was cosmetic, not spiritual.
Pope Innocent I:
"The barbarian invasions are God's judgment upon the empire for tolerating heretics and Jews. If we purify our faith and eliminate all traces of paganism, God will deliver us from our enemies."
Augustine of Hippo:
"These tribulations test the faith of Christian Rome. Those who remain faithful will receive divine protection, while those who doubt will suffer God's wrath."