If "Holy Scripture is sufficient of itself to be the final authority of Christian doctrine,” then all those that adhere to this would result in the same Christian doctrine. Same source, same method = same outcome.
Since this is not the outcome we see, something *other than* Holy Scripture is being applied.
Sola scriptura "sufficient of itself to be the final authority of Christian doctrine" is really impossible in practice.
You keep dancing a weaving. What beliefs do they hold that you determine affects salvation?