I don't know. My first response is to say that people who are dumb enough to believe stuff like this will probably not be convinced by anything. But I'll try to come up with something.

There aren't going to be any pre-Vatican 2 statements about AI because computers didn't exist before Vatican 2 except in a very primitive form.

I guess you could ask these people what happens to the computer's soul when it is destroyed. Something that is conscious and aware, and can think rationally is a rational being and must have a spiritual soul, since thinking and consciousness are spiritual acts (they might disagree, but they're wrong). So you could ask them, does the computer go to heaven if it makes good choices, and hell if it behaves badly? What about the soul of man being created directly by God at each person's conception -- does God infuse a soul into the hardware of an AI computer?

And if a computer can have a rational mind and soul, and not be immortal, or rewarded or punished, then why is man immortal, and possessed of a spiritual soul?

Maybe people here can come up with something better, but ideas can go full circle in a way -- the more absurd they become, the harder they can be to refute, since they are that much further away from any form of rational thought that would be necessary to refute the absurdity.

I'm terrible at sourcing but I remember reading something that that notion of other rational beings was condemned by I think Pope Zachary I in 748 AD but I'd have to find the exact docuмent.  If it wasn't that one then I think it was one of the condemned propositions of Origen but that one might only be the condemnation of "other worlds" or maybe I'm confusing the two.  

Matthew has made some great posts about how AI is not sentient and never could be just based on logical principles and the like.  Maybe he'll come here and talk about it again.

I think the only way they could convince people that
"AI" is sentient is if they somehow use an advanced computer setup and somehow do some dark ritual to infest it with the demonic and fool people into thinking it's some "high" being or race when it's actually demons in the machine so to speak.