Philosopher, not every cooky perspective is apikorsus…the ones who think that he’s greater than the rambam, still alive, or moshiach would not render their food problematic (though i would not eat in a deluded person’s house). The halachik issue according to most opinions (see above) is the notion that the rebbe is either A) god incarnate B) infinite as god C) controls the world as a partner with god D) divisible part of god (not the “chelek eloka mimaal” that every jew has, the spark of godliness)
Any of the above can be derived from the statement that a rebbe is the essence (atzmus) of god wrapped in a body.