Open this photo in gallery: A protester holds a sign following a rally calling for a ceasefire in Gaza, in Toronto on Oct. 23.Arlyn McAdorey/The Canadian Press Justin Trudeau has been stalwart in supporting Israel during the current crisis, despite divisions within the Prime Minister’s Liberal caucus. Pierre Poilievre’s Conservatives are unequivocally pro-Israel. The NDP, though more ambiguous in its position, also condemned the horrific attacks by Hamas of Oct. 7. But Canada is changing, politically and demographically. Some who defend the rights of Palestinians use language that is plainly antisemitic. People are saying hateful things during pro-Palestinian demonstrations. For...