A problem with an excessively dualistic approach to ethics (or politics) is that it can seduce people into believing that they are in the right simply because they’re on the right (religious or political) team. When the truth is we all fall short.
This is not to suggest that there is never a moral distinction between one path or another, or that we all fall short to the same degree, or that we should always be seeking compromise over every issue. But it is to suggest that life is rarely so absolute, that there are often more shades of grey than people care to admit, and that people telling you otherwise are probably lying or lacking in self awareness.
A consequence is, even when you think you’re in the right, you should still humbly be looking for how you can do better.