To be loved is important as is having a sense of accomplishment but to love is equally important in life especially when it is combined with taking action to do something for someone else to make their life better.
The very least you can do in your life is to figure out what you hope for. And the most you can do is live inside that hope.
I can't really put it in one sentence because although on one hand Preacher is about faith and yes it is also about, I suppose, the search for God, the search for faith and the manipulation and the abuse committed by figures in whom I suppose people have faith.