Let’s say that the historicity of the Book of Mormon could be demonstrated irrefutably. (Say that Nephi returned in a cloud of glory, held a press conference, and pointed us to incontrovertible archeological proof.) Would I tune in to watch? Yes. Would this convince me to join or stay in the church?
No. Not even close.
Let’s say that the existence of supernatural beings like angels or life after death could be demonstrated irrefutably. Would this convince me to join or stay in the church?
Let’s say that an angel personally visited me and commanded me to be a Mormon. Would this get my attention? Yes. Would this convince me to join or stay in the church?
There is only one thing that could convince me to join or stay in the church: the extension of grace, the reception of forgiveness, the discipline of consecration, the reality of conversion — and all of it here and now and in plain sight.
That is the only thing that would convince me.
Does existence or historicity prove anything about redeeming power?
No. Nothing. Zero.
Only redeeming power proves redeeming power.