I disagree. Or rather, I don't think this is about doing science.
In many aspects of our lives we rely on the advice of experts. Personally, as I am not a trained biologist, I am unable to reliably decide if the arguments here are right or wrong. I also believe the vast majoriy of people are in a similar position.
As a result, the only options are to look at:
1. The scientific consensus.
2. The legitimacy of the people making the claims.
In many aspects we rely on multiple and competing opinions from various experts. It's not unheard of to go see half a dozen or more experts for treatment recommendations from various experts on a disease. Covid is a novel virus, so nobody has any more than 6 months or so of experience with this particular virus. So first of all, the rush to consensus is a mistake for a novel virus. Secondly, ascertaining the origin of a virus is not something that you garner from consensus. It takes serious investigative work that may take years.
So, again, consensus is just a way to cast complex, nuanced topics as flat, solved for things. That's not the case in most scientific subjects.
#2 is not what remains. You can engage with the arguments and the logic. Even as a layperson.
It is very easy to find out whether someone is an expert, as long as you really want to and don't just fool around. For example, an expert on viral diseases will have a long track record of publications in highly acclaimed journals for the past 30 years or longer.
For the purpose of validation or expert testimony, there is no need to consider everyone who has a PhD and got tenure an expert. It is reasonable to set the bar very high.
The expert on catholicism example is a needless distraction. Of course, there are such experts on catholicism, and they can tell you best what catholic doctrine says. Their opinions about virology are obviously irrelevant, though.
By your measure, Professor Ferguson at ICL is an expert in predicting diseases. He's got a big team and has been doing it for more than 20 years. Many published papers. Invited repeatedly to advise world government's due to his expert status. Widely asserted to be the best in his field.
Guess what - it appears every prediction he ever made was wildly wrong. His predictions for COVID were also wildly wrong. His code was released and it was full of severe bugs. He told the world millions would die of COVID and then when they didn't, claimed his expert recommendations had saved them, all in a fraudulent paper that assumed as a prior that the virus in Sweden mysteriously behaved totally differently to everywhere else and that only lockdowns can possibly affect the course of an epidemic (despite knowing that it isn't true).
This guy has been a failure and fraud his entire life. So has his entire field. It's not just him. All the expert epidemiologists produced models that failed to track reality in any way at all.
Yet, he's an expert by any proxy metric you care to pick. His colleagues rally around, his university protects him, Nature magazine published apologetics for him. He's an expert, unless you pick the only test that matters - are his papers correct?
I know it's scary. But decades, perhaps centuries of near sheep-like behaviour towards science and academics has led to their institutions being saturated with incompetence and fraud. They have no working institutional mechanisms to detect or clear it out. That's why so many fields have "skeptic" movements that "deny" the science. Usually they aren't actually science-deniers as painted, they're people who expected the so-called science to actually care about the scientific method and do their sums right. When they discover that it isn't happening they blog about the errors they found, and the next thing they know, they're being demonised by the press and the very self-same scientists they're criticising. Not because they are wrong, but because they are dangerously right.
In many aspects of our lives we rely on the advice of experts. Personally, as I am not a trained biologist, I am unable to reliably decide if the arguments here are right or wrong. I also believe the vast majoriy of people are in a similar position.
As a result, the only options are to look at:
1. The scientific consensus.
2. The legitimacy of the people making the claims.
It's too early for 1, so 2 is what remains.