There’s some gross-out stuff (buncha fart jokes). Nothing too gory, though kids may be disturbed when the aliens take off their human suits. (The premise is that aliens kill humans and use their image to sneak their way into government positions.
The Slitheen pretend to be human so they can destroy the world. How is that similar to the way demons work?
How does the Doctor defeat the Slitheen?
The Doctor won by exposing the schemes of the Slitheen. He then freed earth of any hold they had. How is this similar to what Jesus accomplished?