"This doctrine of the Kingdom of Heaven, which was the main teaching of Jesus, and which plays so small a part in the Christian creeds, is certainly one of the most revolutionary doctrines that ever stirred and changed human thought. It is small wonder if, the world of that time failed to grasp its full significance, and recoiled in dismay from even a half apprehension of its tremendous challenges to the established habits and institutions of mankind. It is small wonder if the hesitating convert and disciple presently went back to the old familiar ideas of temple and altar, of fierce deity and propitiatory observance, of consecrated priest and magic blessing, and these things being attended to reverted then to the dear old habitual life of hates and profits and competition and pride. For the doctrine of the Kingdom of Heaven, as Jesus seems to have preached it, was no less than a bold and uncompromising demand for a complete change and cleansing of the life of our struggling race, an utter cleansing, without and within."