Yeah, in action. Very easily. It's just like the way the devil teaches evolution. It is stated as theory in the first five seconds and ever after referred to as though it were a fact. The reason behind the stance is that the illusion of an unbroken Papal line is more important to you than people knowing the truth. And the truth is that the office didn't exist at all in Christ's time, nor did it exist at the time of Constantine or Theodosius, ... It's a lie. It's akin to saying Chief so and so in America was the first president of the United states 300 years before Columbus landed because we invented the office for washington; but, wanted our claim bolstered against the British by showing ownership of office and land titles in this country to prove it didn't belong to the Brits. You'll note that We didn't do that. We had a just cause here in rebelling against Britain. You guys just defrauded the world and went on because truth doesn't trump ambition for your clergy.
That's YOUR shorthand. But then again, you're abusing/stretching/changing the definition of 'infallibility.'
The issue isn't infallibility. Get out of Catholic answers for a few seconds and into the conversation. The issue wasn't infallibility. The issue is filling gaps with Antipopes where no actual pope existed and pretending there's an unbroken line. That is fraud - Or fraud on top of fraud as it were. But if you're going to do a great big fraud, a minor one like this is no problem, right..
This should be your new tagline, it suits you beautifully.
...nor did it exist at the time of Constantine or Theodosius
Theodosius? Which one? Theodosius I (reined 379 - 395) or Theodosius II (reined in the Eastern empire 402-450)?
It would be interesting to have a discussion on the issues, but when our friend can't get the base facts of the period correct, it makes it more of a challenge.