Bicom chief executive Lorna Fitz-simons told 400 supporters of the Leeds Lobby Network at Etz Chaim Synagogue: "The most powerful tool in our democracy is writing a letter."
The former Labour MP praised the reaction of David Cameron when the Israeli embassy in Cairo was attacked. "Our PM was one of the first world leaders to say: 'This is outrageous. It won't be tolerated and it has to stop now.'
"But how many have written to the PM to thank him? People are very quick to complain when things go wrong but very slow to praise when leaders do the right thing."
The meeting was chaired by LLN chairman Mike Fligg and attended by members of other faith groups.