Originally the group itself are not muslims even though they call themselves nation of 'islam' and muslims, they may have african roots as muslims and all that fine, but as far as knowing or following islam they are not. Their religion was made up and labelled as 'nation of islam' when it actually goes against hte very fundemental teachings of islam which is absolute monotheism, their early teachings thought that God came in human form for instance as Muhammad Elijah (or whatever that founder was called I forget) and their whole preaching was about ultra black nationalism more or less, in reaction to the oppression of blacks in america.
When Malik El shabas, malcom x, went for hajj, he learned about real islam and saw all people of the world praying together and loving one another during his hajj, he embraced real islam.
As such his ideas posed a threat to both NOI and the US government so they both plotted together to assasinate him which is what happened.
The son of the founder of NOI supposedly embraced main stream islam and reformed NOI, however in reality they are still an offshoot they tried to 'fix' the NOI to be more like islam but in essence there is only one islam and that is that. There are many NOI converts to Islam and they talk about the differences themselves. I knew of one guy who was NOI and left that group and embraced Islam.
They pretty much thought racism against whites while Islam teaches against racism period.
“People don’t realize how a man’s whole life can be changed by one book.”
Malcolm X