Salam.
Muslims don't consider the 'Nation of Islam' to be within the fold of Islam.
There are several things which someone who claims to be a muslim must believe in, these include Prophet Muhammad (pbuh) as the last and final messenger. These believe Elijah Muhammad is a Prophet and so have already deviated.
Other facets of the 'Nation of Islam' are highly against Islamic teaching. For example, the concept of black superiority. Prophet Muhammad (pbuh) said that 'no white man has superiority of a black man, and no black has superiority over a white man, no arab has superiority over a non-arab and no non-arab as superiority of an arab'.
Muhammad Ali and Malcolm X are two very famous examples of members of the 'Nation of Islam' who became true Muslims afterwards.
The story of Malcolm X is my favourite, he taught violence and hatred against non-blacks, he campaigned long and hard for a 'seperate black stated'. He advocated aggression on so many levels.
However, when he went on Hajj (pilgrimage) and saw Muslims, from all creeds and beliefs, praying together. He said: -
There were tens of thousands of pilgrims, from all over the world. They were of all colors, from blue-eyed blonds to black-skinned Africans. But we were all participating in the same ritual displaying a spirit of unity and brotherhood that my experiences in America had led me to believe never could exist between the white an d the non-white...America needs to understand Islam, because this is the one religion that erases from its society the race problem.
Once he returned, he admitted his faults and publicy talked against them, teaching that blacks and whites could live peacefully. This aggrivated the former NOI members and led to his assasination.
Hpe I explained a bit about the NOI.