Again, life expectancy had nothing to do with religion. Its stupid to put the blame of low life expectancy on religion. 1400 years ago life expectancy was low even in areas where religion was not practiced. No connection with religion. Plus why are you comparing living standards from two different eras? of course they are going to be different. A person considered rich 1400 years ago is not going to have the same amount of wealth as the richest person of the modern times. Same goes for states. You are judging history on today's standards. That is unfair. If the whole population of a state was able to get 2 meals a day 1400 years ago, that is better than today where 60% can afford 3 meals and the rest cannot afford even 1. The menu of the meals is irrelevant.
Saudi Arabia, Kuwait, UAE, Oman, Malaysia, Turkey, all of them cannot be outliers. Too many outliers here.
Human progress with time adds things on menu and in life. That is regardless of the practice of religion. The ability of a system is judged on the basis of how the facilities available at the time are distributed among the people, specially the less privileged. And in this regard, modern states are no doubt rich or super rich, yet wealth is divided unequally and the gap is increasing with every passing day.