The capacity of a human mind to believe devoutly in what seems to me to be the highly improbable — from table tapping to the superiority of their own children — has never been plumbed. Faith strikes me as intellectual laziness, but I don’t argue with it — especially as I am rarely in a position to prove that it is mistaken.

Robert A. Heinlein (1907-1988) American writer

Stranger in a Strange Land, ch. 18 (1960 ed., publ. 1991)
    (Source)

An elided version is found in the 1961 published edition, in ch. 13.