You have to take into account the context. Imagine that in the United States, at the peak of the war on terror, people started converting en masse to Islam. A very strict government would see it as the enemy gaining traction in the home turf. Not unlike the conflict between Catholics and protestants in Ireland. The idea was to keep national unity and become free of foreign ideologies.

I am not saying they were right, just that it was not done on a whim. That aspect is even seen in the movie Silence (2016), that is why it's so brilliant.