C. S. Lewis on religion as a private affair

Lewis writes in his essay "Membership":

That religions should be relegated to solitude in such is age is...dangerous for two reasons. In the first place, when the modern world says to us aloud, "You may be religious when you are alone," it adds under its breath, "and I will see to it that you are never alone." To make Christianity a private affair while banishing all privacy is to relegate it to the rainbow's end or the Greek calends. This is one of the enemy's stratagems. In the second place, there is the danger that real Christians who know that Christianity is not a solitary affair may react against that error by simply transporting into our spiritual life that same collectivism which has already conquered our secular life. That is the enemy's other stratagem.

The Weight of Glory. Harper One: New York, NY. 1980. p. 160-161