Understanding is the firm basis on which any intelligent discussion of the differences in religious belief can be pursued. Here is a compendium of the essential facts about the principal churches in the United States put together by a learned practitioner in the ""dialogue"" which will help educate and inform. With charity and objectivity, Father Gustave Weigel, S.J., perhaps the most prominent ecclesiologist in the country, describes for Catholics what others believe against the background of a brief history of the faiths and founders. It will probably come as a surprise to many to hear that there were divisions within the Christian church from the earliest days after Christ and that there was at no point in history an unbroken union among those who called themselves Christian. Every religion from pre-Christian times, the early heresies, the Reformations -- both Protestant and Catholic -- through moral rearmament- is given succinct but adequate attention. Distinctions between the Eastern churches, in and not in communion with Rome, are made clear. This is indeed a book which will serve in these days of the ecumenical mood (with the Vatican Council scheduled to convene sometime next year) to supply a source for serious study by all Catholics of the various churches in the United States, with emphasis on friendly understanding. Imprimatur.