The Great Schism
First contact occurs - a real alien race introduces itself to humanity, and suddenly the Church of the Grey is faced with a rather large dilemma:

'Half' of the Church decide that these are the Grey aliens foretold in the first Book of the Grey, and worship them.

The other 'half' of the Church decide they weren't the Grey aliens foretold, and that any aliens they meet cannot, by definition, be the aliens they were waiting for, because the aliens they meet are not gods. They are just aliens, who don't want to be worshipped and can't possibly live up to expectations.

The worshipping 'half' of the Church eventually disappears, most notably when further races are discovered who are no more or less godly than the first contact aliens.

The Fall of the Church of the Grey
Due to the Church of the Grey encouraging its members to "study all the alternatives and make up your own mind", lots of members convert away from the church to another religion as a result of their studies. Examples given are that 2004 members have converted to Judaism (the last in 2498) and 3 members have converted to Mithraism (in 2102, 2333 and 2378).

Near the end of the 26th century, the registered number of members of the church of the grey has dwindled to one, although it should be noted that there are many, many religions in practice at the time, most small in attendance due to their number. The lone member - Renée Thalia - was working as an Orchestral Attache to the Theatrology Department of Saint Oscar's University (on the planet Dellah) and gets caught up in the rather disturbing events that eventually leads to the planets disappearance, although she herself vacates the planet long before this occurs.

The Rise of the Church of the Grey
A form of life springs up suddenly and with no apparent warning on Dellah. These life forms feed off belief, and encourage belief by manifesting themselves as the deities of the local population.

The population falls under a martial law requiring everyone to take up a faith. This is rather tricky for the student populace as most of the religions available are archaic, riddled with contradictions and hard to bluff your way through. The Church of the Grey, being an inclusive religion where you believe what you wish without being wrong, naturally thrives. In the course of a few days Renée Thalia almost single-handidly boosts the Church of the Grey's registered membership to Four Hundred and One.

As Renée Thalia and her fellow conscripts attempt to flee Dellah, one of the life-forms manifests itself as their 'grey god'. When the 'Grey' orders an execution, her and all 400 of her troops turn their weapons onto the creature and burn it to a cinder. The creature was oblivious of the 'Great Schism' that declared the aliens where not gods, and therefore (unlike other manifested deities on Dellah) was no more invulnerable nor immortal than the first contact aliens. It was also unaware that the second paragraph of Renée Thalias Book of the Grey significantly read:

"God must always be sought, but can never be found"