On the dogmas of religion as distinguished from moral principles, all mankind, from the beginning of the world to this day, have been quarrelling, fighting, burning and torturing one another, for abstractions unintelligible to themselves and to all others, and absolutely beyond the comprehension of the human mind. Were I to enter on that arena, I should only add an unit to the number of Bedlamites.

Thomas Jefferson (1743-1826) American political philosopher, polymath, statesman, US President (1801-09)
Letter (1816-11-11) to Matthew Carey
    (Source)

Mistakenly identified in some sources as Archibald Carey.