Conspiracy theories can migrate from fringe to mainstream respectability.

Evidence

In recent years, an increasingly influential intellectual consensus on both sides of the Atlantic has presented Europe as a doomed and decadent continent that is being transformed into an Islamic colony called ‘Eurabia’. … What began as an outlandish conspiracy theory has become a dangerous Islamophobic fantasy that has moved ever closer towards mainstream respectability, as conservative historians and newspaper columnists, right-wing Zionists and European neofascists find common cause in the threat to ‘Judeo-Christian’ civilisation from Muslim immigrants with supposedly incompatible cultural values. — Matt Carr, You Are Now Entering Eurabia, 10

Categorization

• DEEPTHINKING: The mechanism by which an outlandish fringe theory gains mainstream traction by recruiting otherwise antagonistic constituencies (neofascists, Zionists, conservative historians) is a durable model of ideological convergence worth sitting with.
• XREF: Echoes The Reluctant Fundamentalist’s treatment of post-9/11 suspicion and identity, and long-run debates about how moral panics crystallise around a feared ‘other’.