Triumphalism loosely put = the attitude that one religious creed is superior to all others. Was that definition invented by someone on the wrong side of things, and was ticked off about being told so?
Since Protestantism no matter the stripe, is 100% man made, by heretical individuals, none of them can claim superiority OVER ANY OTHER no matter who, so I get that.
When any of them denies, objects, rejects, triumphalism of the one Church Jesus established on Peter and those united to him, the Catholic Church, as no better or worse than any of the 20-30,000 + heretical man-made sects competing with Our Lord’s Church, and in effect claiming equality with what Our Lord did, THAT’S why there is a permanent separation for all eternity in the end, that Paul warns them of. At their death as individual souls in those organizations, once they know the truth and don’t change, then Paul says the argument is over. The warnings are over. Separation occurs forever for them.
[ διχοστασίαι ] = http://bibleapps.com/greek/1370.htm = division, schism, dissension, sedition, standing apart from, having formed pointless (groundless) factions and sects, and that describes Protestantism of all stripes.
As the CCC defines schism 2089 Incredulity is the neglect of revealed truth or the willful refusal to assent to it. “Heresy is the obstinate post-baptismal denial of some truth which must be believed with divine and catholic faith, or it is likewise an obstinate doubt concerning the same; apostasy is the total repudiation of the Christian faith; schism is the refusal of submission to the Roman Pontiff or of communion with the members of the Church subject to him.”
Schism describes E Orthodox. And it’s condemned, as is heresy.
You already know this. Note that continued denial or doubt doesn’t let one off the hook.
Rom 16: Paul To the Church of Rome,
7 I appeal to you, brethren, to take note of those who create dissensions [ διχοστασίαι ] and difficulties, in opposition to the doctrine which you have been taught; avoid them. 18 For such persons do not serve our Lord Christ, but their own appetites,[b] … I would have you wise as to what is good and guileless as to what is evil; 20 then the God of peace will soon crush Satan under your feet.
And the consequences of that sin on one’s soul who dies divided from Our Lord’s Church? Paul warns
19 Now the works of the flesh are plain: immorality, impurity, …, dissension [ διχοστασίαι ], … and the like. I warn you, as I warned you before, that those who do such things shall not inherit the kingdom of God.
Paul to bishop Titus
"As for a man who is factious ( αἱρετικὸν heretic ), after admonishing him once or twice, have nothing more to do with him, 11 knowing that such a person is perverted and sinful; he is self-condemned."
There’s that theme of 2 warnings, and that’s it.