“As to the allegation of the Communist that religion makes men passive, we have only to observe that the dynamic power of religious convictions is precisely what prevents a soundly religious person from accepting Communist oppression and Communist mandates. A person practicing the teachings of the Judaic-Christian philosophy will not lie or steal on command. He will not shed innocent blood. He will not participate in the diabolical Communist practice of genocide - the systematic extermination of entire nations or classes. It is clearly evident from the numerous Communist writings that what they fear in religion is not that it makes religious people passive to the dominant class but that it prevents them from becoming passive to Communist discipline. Deep spiritual convictions stand like a wall of resistance to challenge the teachings and practices of Communism. Furthermore, the Communist sees in the dynamic ideology of Judaic-Christian teachings a force for peace which cuts through the vitals of Communism's campaign for world-wide revolution.”

Quoted in "Utopia & Revolution: On the Origins of a Metaphor" by Melvin Jonah Lasky, pg 53. Transaction Publishers, 1976
Attributed

Ritual and Mantras: Rules without Meaning, quoted in An Introduction to Hinduism https://www.google.com/books/edition/An_Introduction_to_Hinduism/KpIWhKnYmF0C?hl=en&gbpv=1&pg=PA12 by Gavin D. Flood, p. 12.

"Ignorance of Death" (1940), line 3; cited from John Haffenden (ed.) The Complete Poems (London: Allen Lane, 2000) p. 78.
The Complete Poems

To Senator Styles Bridges (R-NH). 1948
1940s

Quoted from the preface by Ram Swarup in Gurbachan, S. T. S., & Swarup, R. (1991). Muslim League attack on Sikhs and Hindus in the Punjab 1947.

The Naked Communist (1958)

Said during his exile in Peking, as quoted by Oriana Fallaci (June 1973), Intervista con la Storia (sixth edition, 2011).
Interviews

"My Correct Views on Everything" (1974)
Context: When I collect my experiences, I notice that fascist is a person who holds one of the following beliefs (by way of example): 1) That people should wash themselves, rather than go dirty; 2) that freedom of the press in America is preferable to the ownership of the whole press by one ruling party; 3) that people should not be jailed for their opinions. both communist and anti-communist - 4), that racial criteria, in favour of either whites or blacks, are inadvisable in admission to Universities; 5 ) that torture is condemnable, no matter who applies it. (Roughly speaking "fascist" was the same as "liberal".) Fascist was, by definition, a person who happened to have been in jail in a communist country. The refugees from Czechoslovakia in 1968 were sometimes met in Germany by very progressive and absolutely revolutionary leftists with placards saying "fascism will not pass".

On being told his son had joined the Communist Party, as quoted in Try and Stop Me (1944) by Bennet Cerf
A statement similar in theme has also been attributed to Clemenceau:
A young man who isn't a socialist hasn't got a heart; an old man who is a socialist hasn't got a head.
As quoted in "Nice Guys Finish Seventh" : False Phrases, Spurious Sayings, and Familiar Misquotations (1992) by Ralph Keyes.
W. Gurney Benham in A Book of Quotations (1948) cites a statement by François Guizot as the earliest known expression of this general idea, stating that Clemenceau merely adapted the saying substituting socialiste for republicain:
N'être pas républicain à vingt ans est preuve d'un manque de cœur ; l'être après trente ans est preuve d'un manque de tête.
Not to be a republican at twenty is proof of want of heart; to be one at thirty is proof of want of head.
Variations on this general idea have also been attributed or misattributed to many others, most commonly Winston Churchill, who is not known to have actually made any similar statement.
Post-Prime Ministerial