It seems hard to believe that something could have been part of the faith "once and for all delivered to the saints" if it wasn't believed "always, everywhere, and by all."
Well nothing was never believed "always, everywhere, and by all" in any meaningful sense by all humans in how most would understand such a phrase.
However, we are getting into theology here. So there is change within the Church within time. (This is obviously and I am not going to waste my time discussing it. Anyone who believes otherwise has an enormous row to hoe.) Heck, once there were no humans in the Church. That is a pretty big change.
Saints come into being within time. So "the faith" from some ontological perspective could be understood as once being delivered, but from our day to day perspective the Saints deliver the faith over time to us which they received (tradition).
One of the facts which accounts for the changes in the Church.
People in the Church didn't even know that Yeshua was the Son of God for quite some time. Like millions of years.
Again, pretty big change.
Coming from nowhere, I never understood the typical approach most Christians applied to this dynamic as it seemed pretty obvious from a Trinitarian Incarnational understanding of what the Church that the reasoning typically used was odd.
But since most people are pretty confused about what the Church is and when it began, questions like the above end with entirely confused answers, when really they are not that complicated at all.
Caught this phrase while scrolling down and thought I would pipe up.
It's one of three drums I beat.
The IC? That is a much more complicated question.