This is perhaps the novel's strongest indication that socialism and religion work together as dream-ideals of the modern world.
The problem with this interpretation is that traditional Marxist Socialism
is an atheist philosophy. By pairing it with religion, Conrad may be prophesizing
that religion will continue to be a great motivating force for the People in
the modern world -- a spiritual ideal to match socialism's materialist ideal.
If so, the prophecy has certainly come true, as attested by the religious history
of the Russian people under Communism in the 20th Century. But Conrad may be
saying something else. Socialism bears more than a passing resemblance to Catholicism
in many ways, such as its assumption of Original Sin (Man's innate desire to
hoard surplus wealth), its dogmatic, staged approach to history (with the Revolution
coming as surely and objectively as the Judgement Day), and its vision of a
heavenly afterlife or future in which all strife dissolves into universal fulfilment
for all. In this sense, socialism is not merely the "friend" of religion
but is in fact its "humble servant," in that religion has led
the way both psychologically and historically for the newcomer.