Just a thought…ever see a Muslim ‘extremist’ that didn’t belong to a specific sect? That’s the thing with sects, or aligning with specific sub-groups of Islam, or giving your iman a label. It’s the same with nationalism, or pledging allegiance to any specific sub-group of a broader movement. You’re automatically inclined to defend the specific view points of that sect rather than remaining objective and neutral in your application and compliance with the rulings and principles of the movement itself.
The same is true for the raging debates between different sects and different schools of thought. You’ll be hard pressed to find someone that sincerely debates to arrive at the truth, rather than debating to defend their allegiance and adopted perspectives from the sect that they’re a part of.
I can’t see anything other than three specific states of iman. We’re either guided Muslims, misguided Muslims, or non-Muslims. All the nuances and differing opinions around issues that do not take one out of the fold of Islam are simply whisperings of Shaytaan that successfully sow discord amongst Muslims by instilling a sense of pride or superiority in us about our alignment with what is considered by some to be a superior manner of practising Islam, not realising that our pride and haughtiness, no matter how we disguise it, could easily negate all our efforts in the process.