Art is a human creation bound to a person's humanity. Life and art are inseparable. Art is the expression of one's innermost being and covers everything from the way we decorate our houses and whistle a tune to Van Gogh's Starry Night and John Lennon's Imagine. Art covers the whole range of human expression.
Art as a means of propaganda (eg evangelisation) is no more than kitsch (low art). Such a utilatrian view of art is a form of prostitution and a misuse of one's talent. In fact, an artist makes a body of work and that body of work represents his world-view. One piece in the body of artwork does not express the full view for it is impossible for any single work to represent the totality of an artist's view of reality.
The value of an artwork does not depend upon the morality or belief system of the artist. As George Orwell stated "One ought to be able to hold in one's head simultaneously the two facts that Dali is a good draughtsman and a disgusting human being." (The Penguin Essays of George Orwell)
An analogy can be made with a tree. A tree has many functions. It casts a shadow. Birds build nests in its branches. Trees produce oxygen and can be used as wood. The meaning of the tree is not in these functions. The sum of the functions is not the meaning of the tree either. If it does not realise some of its functions that does not mean it is not a tree. Rather, being meaningful, it has many functions.
Art is to be enjoyed because it is art. It is a mark of people's creativity and what it means to be human.