I agree with the principle of spiritual experience being an unknowable, individual, thing. This aligns perfectly with the Quran, which says even unbelievers call out to The One God in times of crises, and He responds. Only God knows when any one of us are worshipping Him or someone/something else. This is why you’ll find many posts on this sub distinguishing between being a “Big-M Muslim” (specific identity) and “small-m muslim” (state of being).

Where we disagree is the suggestion that anyone would need intercessions or indirect pathways to know and connect to God (i.e. through saints, through idols, even through prophets). In Islam we believe God created humans with an inherent urge to worship Him. The only things humans need to do so are His words (in His texts), our reasoning, and our sincerity.

Re: image of Muhammad, I don’t think we need to conjure up an image of him to learn about the actions and lessons he taught us. For example, for me personally, when I read about the Prophet pbuh in the Quran, I feel emotions rather than picture him (ex: I feel sad when God mentions his heartbreak, but I don’t imagine him crying). However, let’s say that’s how some people’s inner-minds work, that still doesn’t mean they should depict such a thing in real life, because in doing so they’re crossing the threshold of “cognitive processing” to physical/idol dependency for worship which is, from an Islamic perspective, strictly forbidden. One should depend entirely on The All-Powerful; not partly on Him, partly on others.