"Protestant" doesn't mean that. "Protestant" means once "saved", always "saved" according to some posters on this forum.
It’s my understanding that early princes of the church opted for infant baptism as a life long guarantee. Later, though, they came believe that sins committed in a state of grace, i.e. post-baptism, were more serious that sins committed while unbaptized.
To counter this, they moved baptism up until older age so as to have less of a spiritual burden at death. That worked until someone fell of his horse, smacked his head into a rock, and died unbaptized.
The solution was to go back to infant baptizing, but to ‘discover’ a post-death/pre-judgement period where sins committed in a state of grace could be worked off. Thus, purgatory.
You seem to have confused "protestant" with Christian.
Then you don't know what Arminianism is, or Anglican, Episcopal, Methodist, etc. These denominations say that salvation can be obtained by anyon, but that experience shows many who have received it by infan baptism or enthusiatic knowledgeable profession can lose their status by not following their tenets.
On the other hand, Presbyterians/Calvinists they say salvation is not for everybody, that only some particular humans selected by God get saved and that for ever, and that others who can never get saved need not apply.
No offense, but I can see that your scope of theology can be extended.
I count myself to believe according to the gospel and its implementation as in the beginning New Testament era; salvation of which everlasting absolute life is a freely obtained feature based on faith-based repentance, with furthering of the new status by local independent autonomous Bible-preaching that recognizes the ordinances of water baptism into discipleship as a certified member of the local assembly professing in servanthood to Jesus Messiah and Master, and communal partaking of the Remembrance Supper of the tokens of Hesus' death on the cross, till He come.
A true local ordained gathering of Christ-followers is administered under the polity of a plurality of coequal elders recognized for their spiritual maturity, into whose care both the welfare and church discipline is entrusted.
That culture is neither catholic (with or without a capital C), nor is it a reformed adaptation of the Roman Catholic theology circa 1500 AD, nor is it protesting Catholic lordship over a state's religious population. It is neither Catholic bor Protestant, but it has been globally present for a long, long time, perpetuated by faithful recruitment of disciples for The Christ.
I hope that clarifies my position somewhat.
And who told you that?
Could you provide the link to those comments please?