Drink the Kool-Aid
To fully embrace the company ideology, uncritically. Derived from the Jonestown tragedy, a fact the phrase's casual users mostly don't know and its recipients occasionally do.
Heard in the wild
“He's fully drunk the Kool-Aid — quotes the mission statement at dinner.”
Tone check: Danger
Dark origin, casual usage. Some orgs find it offensive; 'true believer' carries the meaning without the history.