Speaking as a polytheist (Pagan), I suspect their fragility is fueled by a fear that failure to believe in rigid interpretations of Evangelical Christianity would result in eternal damnation. They try to conceal that fear with a sheath of armor where they claim to be "speaking the truth" (and attempting to convert others) due to (what they self-interpret as) love and sincerity.

Underneath that purported "love and sincerity" are terrified little children scared shitless of the unknown.