I got interested in the early Church heresies when I read Flaubert's _Temptation of St. Antoine_ years ago. It's hard to read up on them because the Church destroyed their texts, and most of what we know is summaries by the early Church Fathers that prefaced refutations. We loosely summarize those quite disparate sects as "gnostic".
My impression was that sectarianism in the early Soviet Union bore a lot of similarities. Minor differences in beliefs, sometimes no more than style, become orthodoxy if a bishop of an important city, or an important party boss, succeeds in establishing his sway.
Sectarianism seems to me to be a natural thing. But why does one sect succeed while others fail? I think Elaine Pagels (I forget the title, something with Satan in its title -- she's an expert on Gnosticism) has it right: Those beliefs that encourage and strengthen organization become the established belief. Other beliefs that promote individualism instead of organization become the heresies.