Enslave a people, make their life hell on earth, and they will turn to some kind of religion.The thought of an afterlife,where things are ideal keeps them going.

This article omitted Hispanics and Muslim Americans, and it's tonality reads with a huge confirmation bias , to me. But consider the indoctrination process that the Spanish did to the Mayans. It runs parallel to the indoctrination of the slaves that where brought here. It all plays out as populace control to me.

From the achtypical Black Baptist Church, it would appear that there is a strong sciological component of social reinforcement.

This makes me sad because when Africans were brought to the Americas and forced into slavery, they lost their culture and identities, including their religions. Christianity was forced onto slaves as a means to control them and keep them under the slave master's thumb. Christianity promotes slavery, the "dark skin is evil" nonsense, and the false notion that if a slave was well behaved they would finally receive their reward in heaven.

Do you mean with the percentage or with the allegation that these people are absolutely certain that a particular entity exists?

And with slavery being condoned in the bible, this utterly confuses me.

There was a time when I was, through the influence of my parents and "tribe", absolutely certain god existed. As a very poor family, the prayers usually centered around "Help us make it through the month". Eating wasn't a big problem since gardening, foraging, chickens and cows were a part of everyday life. People with no power and little hope of improved circumstances automatically seek something "other" in which to believe. During most of a truly dismal marriage, I prayed for change, for strength, for enough love to make it work. I guess my prayer for courage took, because I finally ended it. Awakening to my inner quest, rather than focusing outwardly, led me to my current spiritual state. To all who believe and really live their beliefs, I say, Good for you, do what works for you.