The Short Version
No credible source defines "mécroyance" as a structural cognitive condition or attests the formula M = (G + N) − D. Authoritative French dictionaries (CNRTL, Littré) define "mécréance" as religious unbelief or infidelity. While psychology literature acknowledges sincerely held but erroneous belief systems, none uses this term or equation. The claim presents an unattested, fabricated concept as though it were an established definition.