I think that fighting about doctrine and interpretation in religion is probably like this.
The difference of following programs between
int a[100]; for (int i = 0; i < 100; i++){ a[i] = i; }
and
int a[101]; for (int i = 1; i <= 100; ++i){ a[i] = i; }
absolutely unforgivable for me.
----
For example, C/C ++ and Python do not fight in my mind.
For me, the above two languages coexists friendly.