I generally think of someone who is spiritual as being someone who loosely or passively follows a religion. Someone who doesn't actively or regularly attend church, but may join friends or family on special occasions. A spiritual person may not confine themselves to any one particular religion, and they may not even be very knowledgeable of the bible. In general its a person who does not make religion a primary focus in their lives. It could also be one step short of agnosticism or atheism. Spiritual is not well defined in general, and the idea may vary from person to person.