>>718927931
Faith is also a powerful force that is not understood by many. The Sisters are not psykers but use Faith as their shield and weapon which they are able to manifest into victory on the battlefield.
Faith, faith. 10,000 years of faith from trillions of humans and even some millions of Xenos who believe the Emperor is a true God has super charged him.
People thought he was dying and diminishing, the throne is failing but they don't realise the Golden throne is the only thing that is currently saving Chaos from being obliterated as it's the only thing that is currently shackling the Emperor to the material Universe. Once it fails the Emperor can truly die (Yes Terra will implode and be sucked into a black hole but Terra had it coming) but then as a Perpetual he will be reborn and from that supercharged power of faith he will be the new God of the Galaxy, a true being far, far more powerful than any of the Chaos Gods or all of the Chaos Gods combined.
They know this which is why they send their agents out to help the imperium to maintain the Golden throne from failing.