Jim Wallis of Sojourners
Jim Wallis is a far-left religious leader associated with Sojourners and with Christians for Comprehensive Immigration Reform. He's a past or present Marxist; see this. Currently serving on Obama's Faith Based and Neighborhood Partnerships advisory board.
Discrediting Wallis over immigration matters would be easy and would have a great impact on the abilities of religious leaders to support illegal activity. His parishioners should be urged to publicly confront him (on video) with tough questions about his positions.