I might also add, that I think the term "Stargod" may have not have had as much religious connotations as some some people think. The C'tan were the answer to the Necrontyr's "prayers" in a sense. Powerful entities which could turn the tide and help them defeat the Old Ones once and for all.
Unfortunately (for them), I think the C'tan themselves took the term a bit more literally than they'd intended, particularly the Deceiver, and ended up demanding worship, and sacrifice, and enjoyed it so thoroughly that they turned the entire Necrontyr race into their own personal religious slaves.
So no, I don't think the Necrontyr necessarily were 'religious' in that sense. They just were extremely appreciative of the power the C'tan represented, and naive about where that path would lead.
"-That is all."