As Christianity took hold in Rome following the dream that inspired Constantine to declare it acceptable, lawful and primary within the empire, church fathers imposed their political will.  Christian orthodoxy became the law of the land, all unorthodox believers subject to extreme punishment or death.  Huge numbers were forcibly baptized, making them subject to the will of the Church.  The results of this oppression suppressed free thought and led to the destruction of the learned texts and knowledgeable thought of the previous 500 years.  As these dark ages persisted literacy disappeared and western civilization reverted, learning replaced by mythical thinking. 

How are things different now?  Strong armed political will push a narrative aimed toward personal enrichment for a few without regard to the majority.  200 years of intellectual progress opened myriad ideas producing unprecedented cultural and technological innovation in a truly pluralistic society is being attacked.  The xenophobic fears of a populous looking backwards are in danger of finding themselves living in the kind of closed society that history informs us has been the demise of many earlier civilizations.