The answer, of course, is no, he need not agree with all that they say, and no, he must not hate them. The question is based on a blurring of two different concepts.
Disagreements are legitimate, and sometimes even necessary.
One is obligated to wage a forceful intellectual confrontation against ideas that may destroy the Jewish people. But this is a far cry from an obligation to hate the person expressing those ideas. We must understand that even when an idea is hateful, the man expressing it is not. After all, it is only natural to identify the person with what he says. The answer to this is that it may be hard, but we have no choice but to make this distinction.