Atheism, Religiocity, and Spiritualism

A twist today on the old chestnut, what is the difference between being religious and being spiritual. Can an atheist be either? I was best man a few years back for a dear friend who got married by an atheist rabbi. He was a working rabbi, conducted services and performed rituals. He considered himself deeply Jewish, he just didn't believe in the existence of God. Could he, or someone like him, be conisdered religious or spiritual?