A lot of political concerns overtook religious ones. Some of the religious fights got substituted for political economic struggles, for example the donatism heresy happened because a bunch of berber christian priests were persecuted by the Romans in North Africa and led a struggle against them - and they lost, and instead of martyring some of the priests renounced Christianity. Later when it was safe they rejoined but there was resentment that these people shouldn't be able to do that and they were punished by people saying that these priests shouldn't be capable of giving communion or blessings as they ought to be sinless to do so. Jesus told people that those who haven't sinned should cast the proverbial stone but that teaching was discounted because people were mad that these priests renounced Christianity to save their own hides.