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We could try and introduce the concept of the Righteous Pagan/Righteous Gentile.
There are likely many already such working in forge worlds, workers who are not a member of the cult or necessarily worship the Machine God, but are still productive, respect his machine spirits and abhor the mutant, the alien, and the heretical machine. Laymechanics, Imperial Army Engineers, Agriworld tractor drivers. In fact in 40k basically all of the Imperial populace and many space marines may be considered something like this, they worship the Emperor, or they believe in the old Truth, but they still respect the Machine Spirit.
"‘If any pure machine exists here, then I commend your spirits to the god of Mars,’ he said loudly. He meant it sincerely. Though he had no belief in the Emperor-as-Omnissiah, he respected the machines’ own beliefs." ~Justinian Parris, primaris space marine
The Emperor could be said to be one of them, perhaps the best of them, for he is truly blessed with knowledge and advances the cause and spread of the Mechanicum. Indeed, he gave over Corvus Corax industrial world to them.