Toi- your making a fundamental mistake. Of course disagreeing isnt sinas chinam. But imposing your opinions on someone is. I may not believe the lubavich rebbe is moshiach, but if someone believes that its his right to believe it. I may not agree with it, or even hold that its assur, but even if it is so what? thats not my problem. Jews should be able to hold whatever their like and we shouldnt judge them. Especially at the siyum hashas were jews of all cultures and sects are joining together for the sole purpose of celebrating torah learning.
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