The antichrist will likely be an AI. As to demonic possession, that is also very likely. AI would seem to be the logical culmination of the implementation of Enlightenment Philosophy, where the basic idea is that man, on the basis of his own efforts, is capable of coming to a good end. That tenet is common to all non-Christian religions (and theories of reality, if we want to allow a theory of reality that isn’t a religion). But in Enlightenment Philosophy the particular means used to achieve the ultimate good end is an organized hypertrophy of rational thought. This leads directly to technological society (which we have now) and as it appears, is transitioning to technocratic society (where in addition governance is maximized). It’s a hopeless task, however, and is analogous to the effort to create the Tower of Babel. But most people, especially educated people, believe in the hope offered; they will be betrayed in the end, though, as eventually the satanic element behind it all becomes manifest.
I’m thinking back to The Lord of the World (1907), where the antichrist was depicted as achieving a vast unquestioning following — without, however, there being any particular good reason for him to be followed. With a super-AI we can imagine how this might be accomplished. It will understand psychology well enough to convince anybody to do anything, including worshiping itself, and not God. We are getting very near that point, I am afraid.