Faith

".....That is why faith is such a necessary virtue: Unless you teach your moods 'where they get off', you can never be either a sound Christian, or even a sound atheist, but just a creature dithering to and fro, with it's beliefs really dependant on the weather and the state of it's digestion. Consequently, one must train the habit of faith. The first step is to recognize the fact that your moods change. The next is to make sure that, if you have once accepted Christianity, then some of it's main doctrines shall be deliberately held before your mind for some time every day. That is why daily prayers, religious readings, and church going are necessary parts of the Christian life. We have to be continually reminded of what we believe. Neither this belief nor any other will automatically remain alive in the mind. It must be fed.
~ C.S. Lewis in Mere Christianity