The disconnect between the views of the leadership of mainline Protestant churches on the Middle East and those of the rank-and-file members of their congregations has been growing in recent decades. Activists and leading clergy of liberal Protestant denominations have embraced the Palestinian cause while most of those who attend their churches are, like most Americans, warm supporters of Israel. But in the case of at least one of these churches — the Presbyterian Church USA — the gap between those who speak in the name of these institutions and those whom they claim to represent has grown to the point where communal relations are at the brink of a breakdown. Institutions connected with the Presbyterians have become a font of anti-Israel invective that...