This rather lengthy first volume of a two-volume study of the early church was a very difficult read, not because the material was particularly difficult--one needn't know any Aramaic, Hebrew, Syriac, Greek or even Latin--but because of its organization and the author's writing style. The arguments being made are important, which makes the turgidity of the prose expecially unfortunate.
Basically, this is a book about what occurred amongst the earliest followers of Jesus upon his death. Eisenman associates those located in Palestine with the Ebionites ('the poor'), possibly with the people behind the Dead Sea Scrolls, and assigns their leadership to Jesus' brother James (Yeshua and Jacob being their names transliterated from the Hebrew) and, following him, to other blood relatives. James he tentatively associates with 'the Teacher of Righteousness' in the Scrolls and the movement as a whole he associates with the popular zealot movement which led the unsuccessful revolt against Rome in 66-73. Meanwhile, Eisenman associates some of those early followers who did not dwell in Palestine and who were a mix of Hellenized Jews and god-fearing Gentiles with Paul of Tarsus (Saul) and the authors and redactors of the four canonical gospels and the Book of Acts.
Between the two groups, according to Eisenman, there was great enmity, an enmity covered up, both as regards its basis and as regards its severity, in the accounts of the 'New' Testament. The basis for this conflict was, simply put, that the Hellenized and Gentile followers couldn't accept 'the Way' established by Jesus and his closest circle, including, of course, his immediate family. After the destruction of the Temple in 70, when the gospels and Acts were composed, this simply made political sense. The terrain had changed too much to allow a simple continuation of the early movement. Before the Roman War, however, and at the very root of the conflict's origins, there was Paul, the self-proclaimed 'apostle' who had never met Jesus but who, apparently, was quite influential in building a gentile movement in his name which, by being disassociated from primary identification with the Palestinian movement, was best able to weather the consequences of the end of temple-based Judaism and to influence the formation of what was eventually to become the Christian canon.
Irrelevant to the argument is the author's personally approbative support for James and denunciatory attitude towards Paul--and, for similar reasons, for Josephus. The reasons for these judgments are not entirely spelled out but they appear to include such as the following considerations. First, Eisenman himself has a Jewish background. Second, he identifies Paul and his ilk as being appeasers of Rome and, by extension, imperialism. Third, he (correctly, I think) sees Paul as an upstart turncoat and dissimulator--both he and Josephus being traitors to traditional Judaism. Fourth, he simply may have a proclivity to favor underappreciated historical underdogs which the Ebionites certainly were. Fifth, he may (again correctly) be aggrieved by how the Pauline writings, and the gospels and Acts, have been grist for the mills of anti-Semiitism through subsequent centuries. Whatever his reasons, Eisenmen does not hide his emotions, a practice I find objectionable in a scholarly work. Such motivations are, I think, most properly revealed in prefaces, not in the body of such a text.
As regards readability, I cannot recommend this book. Not only is it too personal, but it is overwhelmingly repetitive, the same points being made, often in the same words, again and again and again. Eisenman may be right in many of his speculations--and they are legion--but he hardly does his cause a favor by hammering at the same nails repeatedly after they have already been driven home.
It is also quite odd, when considering this book as a series of arguments, that Eisenman makes virtually no textual references to the work of other scholars. There are some in the endnotes, yes, but the text itself speaks with but one voice and is, as a result, less convincing than it might be.
Personally, I have long agreed with the primary thesis of this book, namely, that the Ebionites, so decried by the Patristics, originally led by relatives of Jesus, may most closely represent the teachings and practices of Jesus--teachings radically at odds with the Christian churches of today. Eisenman, though much more indigestible than need be, has certainly provided more food for thought along such lines. One just hopes he hires a competent editor and issues a much revised edition of this formidable, but very important, tome.