Is it permissible for me to abandon brothers who marginalize me because I do not belong to a political party, knowing that I am the most knowledgeable among them and they acknowledge that, and given my inability to hold a lesson or a study circle?

It is not permissible to abandon a Muslim or to scorn him, for a Muslim is the brother of a Muslim; he neither wrongs him nor deserts him. The Prophet, peace and blessings be upon him, forbade abandonment for more than three nights, except for a legitimate Shar'i reason. If the party to which your brothers belong opposes Islam or fights virtue, then it is permissible to abandon them. However, if it strives to establish and spread the religion, then this falls under cooperation in righteousness and piety. You must treat your brothers kindly, even if they treat you poorly, for that is among the best of deeds.