The episode has the Doctor, Jamie and Victoria arrive on the planet Telos, where an expedition from Earth has recently arrived, allegedly to do an archaeological investigation into why the Cybermen vanished. But in fact, some of the party have other plans, to find a way to harness the power of the Cybermen to their own ends.
In relation to religion, I noticed that Klieg, the character who thought that he could control the Cybermen, believed that because he had resurrected them and was thus their savior, they would owe him their gratitude and thus their assistance. Cybermen, it turned out, do not view things in that way. But it did seem to me to provide a useful jumping off point for a discussion of whether saving and resurrecting people, or even creating them in the first place, is a sufficient basis for demanding their worship and allegiance.
This was for a long time a lost episode, and then recovered. It was thoroughly enjoyable as an audiobook, and I think now I shall have to make a point of coming back to it and watching it!