Black "Liberation" Theology, like other forms of Liberation Theology, are based on the principle that "God is to be found and understood from among the poor." In other words, because Jesus was "poor" and born to a humble and oppressed people, this is where we should go to seek a proper understanding of God and His plan. This line of reasoning then INEVITABLY emphasizes to temporal condition of the poor over thier spiritual poverty, and equates the Gospel of salvation with that of "political liberation." The language of "political liberation" is dominated by the belief in "revolution" to overthrow the temporal tools of oppression and poverty -- normally in Black Liberation Theology, the WHITE dominated political and economic system -- and replace it with [of course] Marxism. In other words, Black Liberation Theology is the melding together of Black Racism, distorted pseudo-Christian Theology and Marxist-Communism.
It's treatment errs in that theology (properly understood as "the study of God") CANNOT be understood as "coming from" ANY human perspective, but ONLY from the Revelation of God Himself in His Word! Theology from ANY human source or experience viewed as authoritative is going to OBSCURE the truth of God's revelation, NOT express it.
It's treatment err's in that it makes victims of those who see themselves as the oppressed, and it therefore creates in them the false impression that somehow they are OWED [by God or by others] something in return -- and that this "repayment" may be secured by ANY means. Thus, it justifies whatever it's adherents choose to use as a strategy to achieve their own goals. Necessarily, it ignores or downplays the idea that EVERY human is "carnal, sold under sin," or has "fallen short of the glory of God," and instead insists that renewal must come NOT primarily through a personal spiritual "new birth," but by the political and revolutionary overthrow of current systems and governments. Thus, their belief in and support of Marxism -- and too often violence.
This is a PLAGUE, it is a heresy, and it should be openly confronted as such by the Biblical Church.