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When we say, "assuming for the sake of argument," in a discussion, it means we're making an analogy. It is in fact your framing of the issue is dishonest, because you can't prove that lack of support for Israel has kept any country safe, or that it will keep ours safe.
The point is that giving in to a terrorist's demands, merely because you fear your physical safety, is cowardly, and is certainly not a justification for anything at all. You apparently believe that Israel is completely in the wrong. You're not alone in that opinion, and I myself am more conflicted than you seem to think, much as you'd like to paint me with your war monger brush.
That you feel Israel is wrong is plenty justification enough for not supporting their government. Vague fear of reprisal by terrorists is not.