First quoting Chesterton's Orthodoxy, he says that "...of all the horrible religions the most horrible is the worship of the god within. Christianity came into the world firstly in order to assert with violence that a man had not only to looks inwards, but to look outwards to behold with astonishment and enthusiasm a divine company and a divine caption. The only fun of being a Christian was that a man was not left alone with the 'inner light', but definitely recognized an outer light, fair as the sun, clear as the been, terrible as an army with banners..." (pg 26)
Furthering on the point of the gospel, Horton says that "It is not a resource for our self-improvement. Rather, it is a dramatic story that unfolds from promise to fulfillment, with Christ as the center. Its focus is God and his action. God is not a supporting actor in our drama; it is the other way around..." "The gospel doesn't depend on anything in me at all; it is an objective, completed work. The gospel is entirely outside of you!..." "The gospel witnesses not to an inner light within the self, but to a Light that came into the world, shining in the darkness and overpowering it (Jn 1:4-9)" (pg 26)