Christianity is a big tent term that encompasses a lot of differing groups of thought. You've got Catholics and Protestants, being the largest groups that come to mind. Below that you have everything from Lutherans to Presbyterians to Christian Scientists to Westboro Baptists. Admittedly, I don't think I made it clear enough in my comment I was speaking more big-tent Christianity when referring to mary-sue rather than a specific denomination (or a specific church), as I was speaking about religion as a whole, using Christianity as an example, hence why I was saying "Oppose harmful ideas laundered by religion" rather than opposing religion unilaterally. For example, we should oppose the colonialist ideology smuggled through religion, such as forced religious conversions (in order to save their soul!) or the necessity to colonize to do said conversions. We should oppose genocidal rhetoric smuggled through religion. Heck, we should even oppose the shitty bits of text in a religious text like when or when not to stone someone or the punishment for whatever crime.

However, you are implying that you should simply give up your label when bad actors take up your label. While I don't dispute that labels matter, because they do, I think it's silly to just give it up once another person/group tries to coopt your label. If you don't want bigots using your label, you've gotta kick them out. If you change your label to something else, and the bigots come to hide in the crowd, what are you supposed to do, change it for the 5th time?

As far as dropping labels goes, while I like the idea (I hate labels though I find them useful), I think it's impractical. As you said, "there's strength in names," and I think it would be crazy to ask someone to entirely drop a label that they hold dearly, such as their religious affiliation. It would also be crazy to ask them to just say "I believe in Jesus Christ..." and then list out 95 theses to indicate that they oppose aspects of the catholic church, then a good 95 more when they need to indicate their church had a schism in 1893, and another in 1913.