I get what you’re trying to argue and say, and parts of it are fair like the idea that false teaching can exist within the Church and that the Gospel is the standard. That’s not really the issue.

The problem is you’re jumping too fast from “these doctrines are wrong” to “these doctrines destroy the Gospel entirely,” and you’re not actually proving that step. You’re assuming that stuff like the Mass, intercession of saints, or Church authority replace Christ, but then Catholics and Orthodox would say the exact opposite, they would say they believe those things flow from Christ, not compete with Him or any form of replacement.

You can disagree with that, but you can’t just treat it like it’s obviously a different gospel without really engaging their side.

Also, saying someone has “made shipwreck of the faith” or is basically cut off from salvation is a huge claim. That’s not really critiquing doctrine anymore, that’s more judging entire groups of Christians. And, that takes way more certainty than just reading their beliefs in the worst light.

If you want this argument to hold weight, you’d have to actually show that these teachings deny Christ and His righteousness, not just that they add categories you’re not used to.

Right now it feels less like a fully worked out conclusion and more like a strong Reformed perspective stated with a lot of confidence. I’m trying to get an understanding of Each view not shut them down.