You're not a coward; you're human. Here's what I tell myself: There are people who sacrificed far more for freedom than whatever I risk - anger, rejection by some, even my job and reputation. However, I only have one job and one reputation, and I'm not sacrificing them for nothing.
And regardless, taking a dramatic stand rarely accomplishes anything. Listening to others, being curious and open about their positions, and then responding thoughtfully accomplishes much more with much less risk.
> I am no antisemitist, on the contrary, some of my favorite people are jewish.
FWIW, this is a classic line of prejudiced people: 'I'm not anti-X; some of my best friends are X.' There was even a public service commercial in the 1980s that used almost that exact line. Whatever your thoughts, I wouldn't say it. It sounds defensive, for one thing. Say something affirmative - e.g., 'Israelis have a right to peace and justice, as do Palestinians.'
If you are prejudiced (I have no idea; I'm not drawing a conclusion based on one sentence in an online post; and I am certainly nobody's judge), it's ok. We all are to various degrees - the point for me is to be aware that I am human too, that I have this human potential and to be aware of it and notice it, and also to be aware that I also have the human potential for much greater things, and I have a responsibility to embrace that and change my perspective.