If you want to use a definition of religion that requires belief in the supernatural, go for it. But that usage isn’t universal
I said the definition is contested, so you picked your preferred one and declared it "the practical one." Practical for whom? Ethical Culture members with clergy, congregations, and 150 years of continuous practice? Defining religion as "philosophy plus magic" and then citing that definition as your evidence is just assuming your conclusion.
You're welcome to the definition. Just notice you got there by defining the counterexamples away, not by addressing them.