You aren't saying that mentally ill people are starting these fires, are you?
I'm saying that if you allow huge numbers of people whose aggressively evangelical religion dictates that your holy places are an abomination into your country, one should hardly be surprised when those holy places get desecrated, attacked and destroyed.
It seems to be quite the jump from rubbing poo on a cross to burning down the Notre Dame, no?
What do you suppose the modus operandi is for excrement smearing? Do you crap in a bag and take it with you there. Then spread it with a spatula or similar?