I really like the workbook called "World Religions" published by Teacher Created Materials, Inc.  ISBN 1-55734-624-0, which is designed for the higher elementary grades and up.  It covers the basics on Judaism, Christianity, Islam, Hinduism, Buddhism, Sikhism, and Taoism, including the history and origin of each religion along with basic beliefs, symbols and customs.  A page or two of instruction is followed by workbook pages to be completed by the reader.  

There is also a very large website called Religious Tolerance.org which explains the different types of religious beliefs throughout the world.