Through consultation with Clergyman 2, the PCs had narrowed down the list of suspects to 3 possible parties:
1. The Order of Wisdom from the Earth which have a long rivalry with the Church over followers and conflicting theologies. It was speculated that the theft of the artifact might be an attempt to discredit the faith of the Heavenly Sight. The rumors currently flowing around town on the church angering their own deity and the artifact having been taken back as punishment seem to support this theory.
2. The "Unfaithful One" who was banished and just before his banishment was caught trying to taint the artifact with his unholy stain. While more protection had been put in around the artifact after the attempt, the "Unfaithful One" has his own unholy powers and his familiarity with the church would give him a reasonable chance of success in stealing away the artifact.
3. An overzealous patron of the Church who had expressed his desire to house the artifact in his own mansion in 'proper splendour'. It was clear that he had both the resources and the possible motivation for arranging for the artifact to be stolen.
I read this purely as a creation myth without any knowledge of the Locastus setting and liked the way the idea was executed, esp. the first part on the myth of the Grey Lady and the Seir ( I agree with Silveressa's point on the sci-fi terms although personally I just glossed over their actual meaning and interpreted them as being part of the description for a titanic battle with devastating impacts on the world so I didn't deduct any points for this aspect).
Overall, however, I did think this seems like a sub that has enough content to be labelled complete (and is accompanied with good quality write-up) but still lacks something to reach its full potential. In particular, I think the sub would have benefited if you could insinuate more on the culture of the Seir within the creation myth so that they are more vivid as a people. I think that would also address Silveressa's comment on this currently doesn't quite fit into the category of Lifeforms.