
Religion, considered socially, is a more complex phenomenon than science. Each of the great historical religions has three aspects ; (i) a Church, (2) a creed, and (3) a code of personal morals. The relative importance of these three elements has varied greatly in different times and places. ... A purely personal religion, so long as it is content to avoid assertions which science can disprove, may survive undisturbed in the most scientific age.
Source: Religion and Science, 1935, chapt. 1.
More info.: https://russell-j.com/beginner/RS1935_01-010.HTM