Everyone who accepts the teaching of St Paul must have a belief in “sanctification”. But I should myself be very chary of describing such operations of the Holy Ghost as “experiences” if by experiences we mean things necessarily discoverable by introspection. And I should be still more chary of mapping out a series of such experiences as an indispensable norm (or syllabus!) for all Christians. I think the ways in which God saves us are probably infinitely various and admit varying degrees of consciousness in the patient. Anything which sets him saying, “Now – Stage II ought soon to be coming along – Is this it?” I think bad and likely to lead some to presumption and others to despair. We must leave God to dress the wound and not keep on taking peeps under the bandage for ourselves.
From The Collected Letters of C.S. Lewis, Volume II
Compiled in The Business of Heaven