“I hope no reader will suppose that ‘mere’ Christianity is here put forward as an alternative to the creeds of the existing communions—as if a man could adopt it in preference to Congregationalism or Greek Orthodoxy or anything else. It is more like a hall out of which doors open into several rooms. If I can bring anyone into that hall I shall have done what I attempted. But it is in the rooms, not in the hall, that there are fires and chairs and meals.” 

Early in the book, Lewis clarifies his stance regarding the choices open to potential Christians. In one of many analogies, he envisions a hallway featuring doors leading to various branches of Christianity. The hallway is a waiting area, and it is up to each individual to find the right room for them. Lewis warns that this is not just about picking the room that one is attracted to on a superficial level; it is about finding the room that appeals to our conscience and our desire for truth and holiness. In other words, Lewis argues that our moral sense can not only bring us to a belief in God (and the Christian God specifically), but it can guide us to a particular branch of Christianity. This is an important step, because, as Lewis will later argue, Christianity is a communal project in addition to an individual one. Lewis’s aim, however, is simply to offer an argument for Christianity in general, rather than for any particular denomination (though there are arguably moments in the text which reveal his own allegiance to Anglicanism).