It is common in studying "Early Christianity" to speak of christianities instead of a single, monolithic, settled-upon category of "Christianity." In other words, it is wholly anachronistic to speak of "Christianity" in the ancient world because we now know how extremely diverse the "christian" landscape was, including views which ranged from views that upheld the Hebrew scriptures but believed in 2, 3 or 365 gods (Basilides, for instance) to views that saw a connection between the Hebrew scriptures and their praxis/belief by asserting that Jesus was the Jewish messiah to views that chunked the Hebrew scriptures, saw "christianity" as a completely new movement that no connection to "Judaism." There was no "right christianity" in the ancient world that all of these other groups simply "perverted." Instead, varieties of groups sprung up in the years after Jesus lived that interpreted his life, teachings, etc. in very different ways. What many would call "orthodoxy" is, to put it crassly, merely the view that won out in terms of support, both on various local levels and on the imperial level with the conversion of Constantine.
I think this is a healthy way to speak about the first few centuries after Jesus and a move that does not automatically favor one group over another as "right," "true," or the like. Likewise, I propose that we adopt this terminology for talking about "Christianity" today. That is, we would be more accurate and less hegemonic if we spoke of the christianities that exist in one country or another, or the christianities of the world. For to speak of "Christianity" ignores the immense diversity in practice, belief, ethics, etc. that characterize the many groups that self-identify as "Christian" and that are seen as such by others.
I imagine many will push back against such a change in terminology because it fails to recognize "what really is Christianity" or "true Christianity." And they would be right. That is exactly the idea. To be sure, christians can still have intra-group discussions and disagreements about things related to practice, belief, morality, ethics, etc., discussions in which I often find myself engaged, but I am making an honest effort not to speak of "Christianity" as if it is a single entity which can be identified simply and easily, but rather that numerous christianities persist that often look markedly different from one another, yet can still appropriately be described with the adjective "christian."
What say ye?