Its such an easy strategy. All you have to do is find reactionaries on two sides:
Some Protestants think Catholics are not Christians
Some Catholics believe they are being persecuted in their beliefs by Protestants
Now that you have two sides who have made their mind up, all you have to do is introduce that one of those two ideas exists, and even without presenting any facts, you can create an argument that extends far beyond the size of the original two groups. You end up with Protestants that have nothing against Catholics either saying, “Yeah, Catholics arent Christian” or you have them say, “this is not important” which leads to them being considered not “real” as a fallacy. It works the other way two, but it splinters off and changes focus. And it is very effective.
The lutherans here, especially the ones IN THE KNOW are calming the influence of the latter group, thankfully