Certification approval is a mixture of theory, design, engineering, documentation, proof of concept, assessment, and testing self-imposed as a result of successful lobbying to the FAA.
Sorry, I couldn't resist! Seriously though, the trust aspect is a major factor now, especially outside the US.
FAA and Boeing has a bit of work to do in rebuilding this trust, and so far I don't know if there's been much progress. Considering how a "released cargo door" can turn out to be a split fuselage (777x wing loading), I'm not sure how to interpret light stick load in relation to pitch up tendencies of the Max. I would prefer to see results of the bare airframe stall characteristics (as asked for by JATR in recommendation R3.4) before taking Boeings word for what is the purpose of MCAS.