The Fenric Complex
A relatively short contemplation of things.
So, this isn't an original thought, but there are some definite similarities between 'The God Complex' and 'The Curse of Fenric'. Beyond that, however, a lot of those similarities are actually somewhat inverted.
In 'Fenric', faith is the force that keeps the creatures away. In 'God Complex', faith is what draws the creature to you.
In 'Fenric', the Doctor has to destroy Ace's faith in him so that the creature can attack the actual bad guy and preserve its own future world as well as the current one. He has to remove Ace's faith so that the creatures can live.
In 'God Complex', the Doctor has to destroy Amy's faith in him so that he and his remaining companions can escape from the prison, so that they can live. He has to remove Amy's faith so that the creature can die.
In 'Fennric', a man struggles to hang on to his faith and when he lets go of it, he dies. In 'God Complex', a woman holds strong to her faith, and dies. Another woman struggles to hang on to her faith and when she lets go of it, she lives.
In 'Fenric', the Doctor has to lie to Ace so that she will lose her faith in him. The Doctor doesn't believe what he says. In 'God Complex', the Doctor has to tell Amy the truth so that she will lose her faith in him. The Doctor believes what he says.
In 'Fenric', Ace's faith in the Doctor is restored and she continues to travel with him. In 'God Complex', Amy has to see the Doctor as a man instead of a God and they part ways.
Which one is right? Which creature deserves death? Or life? Which episode presents faith correctly? Which Doctor did the right thing? Which companion did the right thing?
The answer to all of these questions is: both.