The negative reviews are little more than religious policing. The one star reviews for Mo are the same one star 'blasphemy' reviews you'll find on The Life of Brian. While Mo isn't a satire - it doesn't mock religion - it works as a comedy because it's about a story of ridiculous contradictions and the distinctly familiar, muddling human attempts to make sense of it all and survive.
99% of the bellyaching reviews are critical of the characters not being Muslim enough, the situations not being true to scripture and strict observance of Islam.
But is this not demonstrably true of most religious people today? Most Abrahamic religions do not adhere to ultra orthodoxy, most seek a modern sensibility because dogma denies the personal purposes of faith. I don't need anachronistic dogma to legitimise my beliefs, in fact I blame it for a lot of problems.
Mo is realistic, modern and deeply funny series that is first and foremost about people. It works because it's about experiences we share as humans regardless of - or because of - politics or religion. It works because it gives a perspective we don't often see but with a humanity that we very much understand.