The book Gods and the One God is written by Robert M. Grant. It is part of a series entitled the Library of Early Christianity edited by Wayne Meeks. This publication attempts to situate early Christian theology within its appropriate Greco-Roman context. But contrary to one of the blurbs that appears on my copy of this work, Grant does not simply document "the similarities and differences between beliefs of the emerging Christian movement" and beliefs held by the "larger world" in the first century or early second century CE. Rather, he seems to argue that there is a sense in which certain Christian beliefs depended on pagan beliefs or concepts about God (i.e., they were possibly shaped or influenced by pagan thought). An example of this phenomenon is when one analyzes what Grant has to say about the gradual development of Christology (the systematic doctrine of Christ's person and work) and its concomitant teaching, the Trinity. Grant argues that the early church fathers were almost universally subordinationist in thought (concerning the relationship between Christ and his divine Father) prior to the Council of Nicaea (page 160). As Grant writes in his description of Theophilus of Antioch and other early Christian authors like him, "we find the materials for such a doctrine [of the Trinity] but not a doctrine as such" (page 156). He also points out that "The doctrine of the trinity in unity is not a product of the earliest Christian period, and we do not find it carefully expressed before the end of the second century" (page 156).
Regarding the structure of this work:
There are three parts to this book and 13 chapters. Grant begins his study with an account of how the Christian God is portrayed in Acts of the Apostles and then discusses how philosophy, Judaism and Christianity depicted God in antiquity. He concludes his study by focusing on divergent Christologies and the Trinity doctrine. I highly recommend Grant's text--it is illuminating, intellectually honest and mainly objective.
Grant, Robert M. Gods and the One God. Philadelphia: Westminster Press, 1986.