The warm tributes to William F. Buckley Jr., the conservative hero who died Wednesday at age 82, have emphasized all that everyone could appreciate about him: the formidable intelligence, the capacious vocabulary, the otherworldly productivity, the playful wit, the graciousness and deep, wide-ranging friendships. He was a beloved figure who had entered American lore and, in that sense, belonged to all of us. But in the fond reminiscences, it shouldn't be forgotten what he hated. Buckley was an anti-Communist to the marrow of his bones, whose lifelong mission was to crush Marxist totalitarianism. In this, he was uncompromising, relentless, and...