It's supposed to convey a certain message. The message surrounding a crucifix in urine maybe a little hazy, but it's a sure bet there's someone out there who understands it. Like all communication, art is a person's particular way of expressing what's inside. To ignore that person's work, is to deny respect to them as a person and to what they have to say. Art can, in a certain sense of the word, help bring about unity.
Art has no boundaries.
Art appeals to the emotions, which is something everybody shares. Trying to define art is like trying to define life, it's very fluid. So does art, and by taking time out to view it, it can help us do the same.