Being Presbyterian doesn't save you; and it's not taught that way as it is in the Catholic Church (no salvation outside of the Catholic Church) --
"An unsaved member of the apostate branch of Presbyterianism" might be the better title.
Hoss
There was an priest in Boston, years ago, who believed it that way, damning all non-Catholics, and preached it. His name was Fr. Leonard Feeney. He was told his interpretation was erroneous and that he should retract his opinion; he defied this counsel; and he was excommunicated in 1953 for his obstinate persistence in this error despite repeated warnings.
We can know who is in the Church; we cannot know, with moral certainty, who is outside the Church.