True (biblical) separation is to imitate God, whose central command to us in this respect runs right through the Bible: ‘Be holy, for I am holy.’ It is unfortunately easy for us to distort the scriptural ideal of separation by developing a life-style which simply sets out to contradict whatever is current in society around us…. The heart of the matter is this: the saint’s separation is not a mere reaction against but a response to; not a mere determination to be different from the world but a whole-hearted determination to be like God by obeying His word.

J. A. Motyer, The Message of Philippians, p. 31