And here at the outset I must deal with an unpleasant business. It seems to the layman that in the Church of England we often hear from our priests doctrine which is not Anglican Christianity. It may depart from Anglican Christianity in either of two ways: (1) It may be so ‘broad’ or ‘liberal’ or ‘modern’ that it in fact excludes any real Supernaturalism and thus ceases to be Christian at all. (2) It may, on the other hand, be Roman. It is not, of course, for me to define to you what Anglican Christianity is—I am your pupil, not your teacher. But I insist that wherever you draw the lines, bounding lines must exist, beyond which your doctrine will cease either to be Anglican or to be Christian: and I suggest also that the lines come a great deal sooner than many modern priests think. I think it is your duty to fix the lines clearly in your own minds: and if you wish to go beyond them you must change your profession. This is your duty not specially as Christians or as priests but as honest men.
C.S. Lewis, "Christian Apologetics" (1945) included in God in the Dock (Eerdmans, 1970) 89-90. This paper was read to an assembly of Anglican priests and youth leaders at the ‘Carmarthen Conference for Youth Leaders and Junior ‘clergy’ of the Church in Wales at Carmarthen.