Members of the group have been influenced by the racist Christian Identity movement that scapegoats blacks and hispanics as an outlet for a long simmering rage over the unrelenting decline of economic conditions in rural America.
Here's a quote from the SPLC's report:
Those sounding the alarm about Joel's Army are not secular foes of the Christian Right, few of whom are even aware of the movement or how widespread it's become in the past decade. Instead, Joel's Army critics are mostly conservative Christians, either neo-Pentecostals who left the movement in disgust or evangelical Christians who fear that Joel's Army preachers are stealing their flocks, even sending spies to infiltrate their own congregations and sway their young people to heresy. And they say the movement is becoming frightening.
"The pitch and intensity of the military rhetoric of this branch of the global Dominionist movement has substantially increased since the beginning of 2008," writes The Discernment Research Group, a Christian watchdog group that tracks what they call heresies or cults within Christianity. "One can only wonder how long before this transforms into real warfare with actual warriors."