Here's exhibit A on how to hurt interfaith relations and in this instance it's between the Presbyterian Church USA and the Jewish community. There was a falling out between these two groups over the the decision to fund a Jewish messianic congregation as well as the selective divestment campaign which targets companies profiting from the Israeli-Palestinian conflict. Efforts were made to engage in some level of dialogue but things ran into a bit of a snag recently when a Presbyterian group decided to meet with a known terrorist organization, Hezbollah, which has killed hundreds of Americans and Israelis.
During the meeting a statement was made from a member of the presbyterian contingent which would prove to be astonishing. Not just because of it's praise of Hezbollah but because of it's attack on Jewish dialogue efforts. "I'd like to say that according to my recent experience, relations and conversations with Islamic leaders are a lot easier than dealings and dialogue with Jewish leaders." Though Presbyterian leaders have denounced the visit and comments I suspect this event will inflict lasting damage to interfaith relations.
Of course producing a split between liberal religious movements, in this case Reform Judaism and the Presbyterian Church is great news on the right and will be exploited heavily, which is a shame. This liberal Jewish/Protestant relationship has been essential for advancing a number of progressive causes and values from the civil rights movement to gay and lesbian equality. To have such a relationship so carelessly damaged benefits the right, but it doesn't do anything to advance a progressive religious vision here or abroad.