The great tragedy of the Jews, as revealed in the Old Testament, was the disparity between the external and internal life; between appearances and reality; between what was professed and what was in fact. Much teaching of Christ was directed towards the Jews, pointing out their failure to be inwardly, that which they claimed outwardly to be.
Paul majored on this issue in the early Church too, warning of those who had a form of godliness but no substance, and John went even further by warning that many anti-Christs had gone out from the people of God. The history of the Church provides all the proof we need that when faith deteriorates into religion, it becomes a front; Jesus is in the shop window, but inside something very different is taking place.
Churches and religious societies founded by godly men with courage, faith and sanctified imagination seem unable to propagate themselves, in the sense of having any spiritual power, beyond the first or second generation. There seems a fatal tendency towards what David Pawson called the “club-type membership” and “the professional ministry” and this inevitably results in a strong gravitational pull towards religious mediocrity.