I think there may be a certain intellectual trend out there that has bought off pretty much completely on the Bauer/Ehrman hypothesis regarding the historicity of early Christianity, and hence discards even very the notion that there may have been anything which
could be rightly called orthodox or heterodox in an Early Church context, even though such a distinction had been standard for
centuries by the time of the Albigensian Crusade, with works written before any of the major Church schisms (meaning those of Ephesus, Chalcedon, or of the Chalcedonians from one another) like St. Irenaeus'
Against Heresies (c. 180 AD), St. Hippolytus'
Refutation of All Heresies (early 3rd century), St. Augustine's various works against the Manichaeans (fourth century; notable because he calls them heretics despite Manichaeism having arisen outside of the Christian church), St. Epiphanius of Salamis'
Panarion (374-377), and many, many others bearing witness.
Such people could do worse than to read
The Heresy of Orthodoxy by Andreas J. Kostenberger and Michael J. Kruger (2011), which meticulously and thoroughly demolishes this baffling yet popular ahistorical way of thinking. Kostenberger is the senior research professor of New Testament and Biblical Theology at
Southeastern Baptist Theological Seminary in North Carolina, while Kruger is president and Samuel C. Patterson professor of New Testament and Early Christianity at Reformed Theological Seminary, also in North Carolina (and also an ordained Presbyterian minister). I trust these associations prove their dispassion in dealing with the material, as such men would certainly not be stumping for either Rome or Constantinople (or Alexandria, or Edessa...just to cover everyone!), or their sectarian views regarding who's right in any particular context. The take home of the research isn't even about that, so much as it is a testament to how the incontrovertible evidence found in the early Church itself utterly destroys the viewpoint of those who would blame an 'institutional church' largely of their own making for whatever imagined problem may have come to this or that people in its zeal to defend a made-up 'orthodoxy' from made-up 'heretics'.
In reality, neither were made up, but the "Trail of Blood" theory certainly is. Not that it is the best of all possible sources, but the general reference website Wikipedia doesn't place it in the category "
Pseudohistory" for nothing.