There was a conference once where Fr. Joseph Fessio suggested (rather humorously) that what united Christians (Anglican, Evangelical, Catholic, Orthodox) was Scripture, the Apostles Creed, the first six Ecumenical Councils, and C. S. Lewis.
It does not take much time talking with Christians of all stripes to see the truth in this statement. There are lovers of Lewis in all camps (though one must acknowledge his detractors, those who find him too Catholic, or not Catholic enough, too Anglican, or not Anglican enough). His writing is intelligent enough – and simple enough – to appeal to a vast audience. He is, in many ways, the Universal Theologian.
There is, however, a problem: ‘Mere Christianity.’ I am not speaking about the book per se, rather, it is the concept which has a problem in itself.
At its most fundamental level, there is nothing wrong with the idea of ‘mere’ Christianity. All Christian’s everywhere hold to it, after a fashion. The problem lies in determining what belongs to the category of ‘mere Christianity,’ and what does not.
For many today that problem has been ‘solved’ by the very man who popularized the concept. In the book Mere Christianity it was Lewis himself who decided precisely what belonged to that category and what did not. As the author that was, of course, his prerogative. One would find it rather silly if he accepted the ‘Broad’ church definition of what was required and it would be disingenuous of him to use the Catholic or Orthodox standards. Lewis himself admitted to having a problem with the word ‘mere’, though not in the book bearing that title.
While it was right and good for Lewis to use his own the standards, it becomes problematic when Christians at large accept those standards more or less uncritically. In this way, Lewis’ virtue of writing convincingly and well becomes something of a vice, enforcing his decision of what belongs to Christianity on his followers (though I would not say he chose to do this maliciously, it was simply the consequence of his skill). There is thus what amounts to the Church Founded by Lewis, the large body of people (generally those without a theological background) of every ecclesiastical community who hold that what is necessary for Christianity is found in Lewis’ small book – though most are not particularly aware of this.
Through little fault of his own Lewis brought about this strange new entity. In some ways it is a positive step on the ecumenical path: Christians today are all the more aware of what unites us. But it is also detrimental in that Christians today are less willing to do anything about what divides us, having come to the conclusion that everything (not absolutely heretical) beyond ‘mere Christianity’ is acceptable but essentially peripheral.
Ultimately what this does is interfere with any honest dialogue, with the attempts to determine just what place Mary, the Sacraments, etc., play in the Christian world. Lewis has done us a great favor through Mere Christianity but we cannot let it rest solely there. It us up to us now to determine just what belongs to the field of ‘mere Christianity;’ what is it that we, as followers of Christ, cannot do without.