Historically, as the other posters mentioned, perhaps the Nation of Islam did once serve as a foil to Christianity, but it no longer holds a place such as that in American society. I have found that most of my students now just know about the Nation of Islam as it is today--an organization that promotes anti-Semitism and that does not hold a place in global Islam.
I feel that #2 ends with an interesting point regarding how both religions were manipulated and (mis)represented for a particular purpose, but also how this presentation fed into popular perceptions of religion and how they are weighted towards extremes. It does acknowledge the role of representation but also identifies other factors in setting up these two approaches as foils to each other. Giving more options to African-Americans and other approaches through which they could express their position was definitely one of the key motivations behind this movement.
I think that the question is an interesting one and can be seen in very clear terms in the Civil Rights struggle in America of the 1950s and 1960s. Leaders like Dr. King and Malcolm X were fighting for the rights of people of color in America and doing so through, in large part, the invocation of different religions. On one hand. the Civil Rights leadership in the South, led by Dr. King, acted in the faith of Christianity. This helped bring a moral note to their struggle. Invoking religious scripture, leaders like King used Christianity to help demonize the enemy in the White establishment figures that denied Black Americans their basic rights as citizens and human beings. They often brought out the idea of not sinking to the moral level of another, a very Christian idea, and "turning the other cheek" in preaching non- violence via civil disobedience. In contrast, Malcolm X and his Nation of Islam followers used the teachings of Islam as interpreted by the Honorable Elijah Muhammed to help bring the idea that there needed to be a forceful change in how Black Americans saw themselves and how the nation saw them. This called for a very strict and orthodox view of the religion that caused a bit of fear in Americans, White and, even sometimes, Black Americans. In this light, the Nation of Islam was set up as a foil to Christianity. Leaders of the Nation felt this was important to call to clear difference the philosophies rooted in Christianity and those in Islam. Other leaders, such as Malcolm X at a later stage of his life, understood that the Islamic faith might be best used as a way to make White Americans understand that embracing the philosophies and reasoning of leaders like King might be the best plan if they wanted to avoid the more harrowing alternative. I think that the differences were needed in order to articulate and speak to more African- Americans who wanted different outlets to voice their anger against the White Establishment. I am not sure the manipulation of one religion as one of pure "love" and the other of pure "hate" was as needed, but more to be expected given how religion is always perceived.