Above: Rabbi Adin Steinsaltz (Even-Yisrael)
Note the letters posted below are not resignations from the so-called Sanhedrin (high Jewish rabbinical court) and are instead resignation letters for Rabbi Adin Steinsaltz's now-former position as its "nasi" (president). But Steinsaltz appears to be a member of the Sanhedrin and appears to still support it, even though his office is claiming today that Steinsaltz hasn't had anything to do with the Sanhedrin since about a week before he sent Rabbi Dov Stein the resignation letter in 2008. But that alleged complete break with the Sanhedrin is not, as far as I can see, clear.
As for Steinsaltz's contention that his name should not be used for Sanhedrin decision he doesn't agree with or is not a part of, last time I checked, dissenting judges on formal beit dins (religious courts) own the majority's ruling even if they disagree with it. That doesn't mean the dissent is necessarily suppressed, but it does mean the rabbinic judge(s) who dissent own the decisions they disagree with unless they resign or publicly announce their dissent – two things Steinsaltz has not really done. Saying, don't use my name without my permission isn't the same as saying I disagree with your ruling for the following reasons and explaining them.
All Steinsaltz's letter says is that he is no longer the Sanhedrin's president and that he does not want Dov Stein and the others on the Sanhedrin to use Steinsaltz's name unless he has expressly agreed. But even in this week's handwritten addition to the letter, Steinsaltz does not say he disagrees with their decision to put the Pope and the Vatican on trial.
And that's likely because his only disagreement comes from a tactical perspective and not from the actual "crimes" the Pope and the Vatican are allegedly committing. Steinsaltz, I think, agrees the Pope and the Vatican are committing these crimes and that in a more perfect world, should be tried and convicted by the Sanhedrin for them.
And that is what everyone should believe about Steinsaltz until he specifically, clearly and publicly says otherwise.
As for why Steinsaltz might think that it is theologically correct to put the Pope on trial, look no further than the racist anti-gentile philosophy of the Chabad-Lubavitch movement he belongs to.
Please click to enlarge: