“I’m one of your loyal readers, but if you don’t change your thinking on this point, you’re going to lose me. The comment is meant to put you on your heels and keep you from questioning whether the person writing actually is one of your loyal readers.

Something stemming from my life experience makes me highly resentful of this form of passive-aggressive interaction".

Walter, I think you are being overtly super-sensitive here. There are many, many other sayings in our complex, troubled world that are far more threatening than what you are complaining about.

Also, I do not see the statement:

“I’m one of your loyal readers, but if you don’t change your thinking on this point, you’re going to lose me", as a form of passive-aggressive interaction.

I think you should embrace it and further elucidate your point to explain why you wrote what you wrote.