Will you please say how you would define a practising Christian? Are there any other varieties?
Certainly there are a great many other varieties. It depends, of course, on what you mean by ‘practising Christian’. If you mean one who has practised Christianity in every respect at every moment of his life, then there is only One on record — Christ Himself. In that sense there are no practising Christians, but only Christians who, in varying degrees, try to practise it and fail in varying degrees and then start again. A perfect practice of Christianity would, of course, consist in a perfect imitation of the life of Christ I mean, in so far as it was applicable in one’s own particular circumstances. Not in an idiotic sense it doesn’t mean that every Christian should grow a beard, or be a bachelor, or become a travelling preacher. It means that every single act and feeling, every experience, whether pleasant or unpleasant, must be referred to God. It means looking at everything as something that comes from Him, and always looking to Him and asking His will first, and saying: ‘How would He wish me to deal with this?’
A kind of picture or pattern (in a very remote way) of the relation between the perfect Christian and his God, would be the relation of the good dog to its master. This is only a very imperfect picture, though, because the dog hasn’t reason like its master: whereas we do share in God’s reason, even if in an imperfect and interrupted way (‘interrupted’ because we don’t think rationally for very long at a time — it’s too tiring — and we haven’t information to understand things fully, and our intelligence itself has certain limitations). In that way we are more like God than the dog is like us, though, of course, there are other ways in which the dog is more like us than we are like God. It is only an illustration.
"Answers to Questions on Christianity," God in the Dock (Eerdmans: 1970) 50.