Why Do Some Question Using Faith as Our Moral Guide?

Salaam everyone, I've been thinking about this a lot. Isn't one of the main points of our deen, especially in Islam, to guide us in every part of our lives, including our character and ethics? The Quran and Sunnah give us that clear direction. So I really don't get why some folks act like it's a bad thing to use your religion as your moral compass. It just seems like the whole purpose. Maybe it's just something trendy to say online that doesn't even hold up. People say all sorts of contradictory things these days, subhanAllah.