Dear anti-Israel campus protesters: Though it may take a few years before you realize it, supporters of Israel like me have reasons to give thanks to militant anti-Zionists like you. Recently, a friend asked what I would have made of your protests if they had been less fervently one-sided. If, for instance, pro-Palestinian student groups at Harvard and Columbia hadn’t castigated Israel immediately following the worst massacre of Jews since the Holocaust. Or if Jewish students and professors hadn’t faced violence, harassment and antisemitic imagery from you or your allies from Harvard to Columbia to Berkeley to Stanford. Or if...