To invade, High Lords need Supporters. Supporters are people who believe that some significant aspect of an invading Reality is real, believe it will shortly become real, or deeply want it to be real.
Example: Transhumanists believe that AI will happen, they deeply want it to happen, and indeed believe it is imminent (within a decade). Some percentage of devoted transhumanists could qualify as supporters of an invading science fiction Reality.
Now, Supporters don’t have to accept all aspects of an invading Reality. Singular elements (so long as they are significant) do qualify.
One element of the Dark Papacy is real miracles from God. If someone believes such miracles do exist or deeply, devoutly wishes they did, they can qualify as a Supporter.
Another element of the Dark Papacy is a Christian theocracy. The more one believes that such a thing is possible or imminent, the greater a chance they might qualify as a Supporter. (Even if they hate the idea of a theocracy, if they believe one is possible and imminent, they can qualify.)
Thus, all High Lords precede their invasion efforts with significant propaganda, designed to convince people to devoutly wish that some significant aspect of their Reality were true, to believe that it is true, or to believe that such a thing is imminent.
They cement this belief with Possibility Energy. Those with devout enough beliefs, who are touched by the PE, qualify as Supporters.
So, what is the Temple?
It is part of the propaganda efforts of the Living Land. This new religion encourages belief in a real Goddess, who wields power over the world. It encourages belief in miracles, the energy of life, and a coming techno-apocalypse. All of these are key aspects of the Living Land.
According to the teachings of the Temple, the world is being overgrown by technological tools and weapons. They choke out life, leach away the joy of living. Devout adherents are encouraged to give up the material trappings of modern existence and take up life on one of the Temple’s many settlements. (Hence the common insult — “Hipster Amish”.)
They voluntarily give up technology, but (according to their beliefs) all people will be forced to, sooner or later. There is a coming techno-apocalypse, which will see the end of technology and the birth of a new age of freedom and life, when the Goddess’ prophets — the Enlightened — return.