"Our decision to deny what was in front of our face--for the sake of our 'greater purpose'"?
The "denial" your refer to is common in highly controlled authoritarian groups. It's commonly understood within the context of cognitive dissonance, which is the process that resolves the conflict between the "red flag" we see and what the leader and group demand we conclude.
Please take the time to read and digest the research on cognitive dissonance, gaslighting, thought reform, coercive persuasion and influence techniques.
This is Robert Cialdini's 6 principles of "Influence" from his seminal book on the subject.
"Little red flags" are often obviated in authoritarian controlling groups by the leader's dominance and control of the environment. It's difficult within that context to get accurate feedback and validation concerning suspicions and doubts.
You allude to a philosophy of the "ends justify the means" to dismiss concerns about the leader's dictates/actions and related group behavior. That is, supposedly for "the sake of a greater purpose."
This thinking reflects the effects of thought reform and group manipulation as identified in the previously linked research.