In the excerpt from C.S. Lewis' Mere Christianity, he discusses the nature of humanity. Lewis discusses that there are not good or bad impulses, but rather simply just impulses and it is how we decide to act that determines whether it is good or bad. Impulses and instincts are like keys on the piano, they sound marvelous when some are played together but when others are used together, it loses its splendor.
Another point that Lewis makes is that, as Christians, we should not promote separation of the church but concentrate on things common throughout the church. For as Jesus is one with God the Father, we too must be one with each other in community. We learn how to act and behave at a young age and we must raise the children and future of mankind based upon Christian virtues and morals.