In 415 CE, the Archbishop Cyril of Alexandria has his monks incite a Christian mob to murder the last scientist/librarian of the Alexandrian Library, Hypatia. The Christians, led by Peter the Magistrate, strip Hypatia naked, drag her through the streets to the Christian church Caesareum, where they flayed her body with ostraca (while she is still alive, they stripped off her skin with pottery shards), tore her body into pieces, and then finally burned the remains.
It was only 391 CE when Emperor Theodosius issued his edict closing down all Pagan temples, which immediately resulted in the temple of Serapis in Alexandria being razed to the foundation. And from there, only 19 years of internal ROT until the Visigoths sacked Rome.
These are the same ideological, fundamentalist Christians trying to get into power in the United States today. This is our History and our near Future if we fail to pay attention to the very clear warning signs of rising Christian nationalism, claims of religious supremacy, and promulgation of theocratic leadership.