He was given in to much fanaticism.

Fanaticism : the quality of being fanatical; obsessively concerned with something.
Reason : a cause, explanation, or justification for an action or event.
Kindness : the quality of being friendly, generous, and considerate.
Passivity : acceptance of what happens, without active response or resistance.
Violence : behaviour involving physical force intended to hurt, damage, or kill someone or something.

Antonym of Fanaticism is Reason