Diversity in Proto-orthodox Christianity

I'm reading through Bart Ehrman's Lost Christianities, and I'm shaking my head against the view that a cartel of proto-orthodox leaders conspired and then successfully executed a plan to impose doctrinal uniformity upon the pluriform and diverse Christian groups spread over the known world. My objection is that proto-orthodoxy was a little more diverse and tolerant than many realize. Towards an eventual big project on this, this is what I've come up with so far:

"Against those that think that the proto-orthodox imposed unity on the diversity of early Christianity, it is crucial to remember that proto-orthodoxy contained a great deal of diversity itself as is evident from the New Testament. A comparison of the Synoptic, Johannine, and Pauline materials provide ample evidence for this point as the New Testament contains a diverse array of voices. Also Justin Martyr knew of Jewish Christians groups that he considered ‘orthodox’. Tertullian could speak up for the Montanists as those ‘enthusiastic men of the Spirit’. The various hymns and creeds of early Christianity, including those within the New Testament (e.g. Phil. 2.5-11) and through to the Apostle’s creed, were not designed to stifle diversity as much as they functioned to give a basic and broad bare agreement among diverse Christian groups. At Rhossus in the early second-century, the Bishop of Antioch, Serapion, was quite willing at first to allow the church there to use the Gospel of Peter in their private readings alongside more recognized texts, it was only after it was found to be congenial to docetic interpretation that he prohibited the document. But Serapion’s de fault response was to give the document the benefit of the doubt. Serapion never explicitly labels the Gospel of Peter as heretical, but merely states that it was conducive to docetic interpretation. The inclusion of the antilegomena (i.e. the disputed writings) in the canon shows that dispute about what writings were considered authoritative had elasticity and some Christians were willing to accept texts that they were not 100% sure about. In which case, we find both tolerance and boundaries functioning within the matrix of proto-orthodox Christianity. Those boundaries did not occur ex nihilio but were already emerging as part of the struggle of Christians to create and discover their own identity vis-à-vis Judaism and Paganism. Thus the proto-orthodox did not impose uniformity across the board, but they did set limits to diversity. What is more, those limits were not created by a numerically small elite that imposed their iron will upon the unwilling majority, but those boundaries were successful only because they resonated with the pre-existent beliefs, attitudes, and convictions of the majority of Christians across the Mediterranean."

© Michael F. Bird