What is the ruling on inciting discord, slandering preachers, and excommunicating Muslims in the name of religion, and what is the way out of it?

A sound hadith (definition) from the Prophet, peace and blessings be upon him, warns against declaring Muslims as disbelievers in general. The matter becomes even more serious when this declaration of disbelief is directed at preachers and scholars. Scholars and preachers must be respected and thought well of, while believing that they are not infallible and should not be blindly followed in matters where they contradict the truth. Nevertheless, one should benefit from the good they possess. If they differ, a Muslim should ask Allah for guidance to the truth, seek out the truth diligently, consult scholars, and follow what seems most preponderant to him, without disparaging the one who erred if their intention was sincere, and without diminishing their status, for a lapse or a slip might occur from them for which they are excused. Furthermore, the texts of warning (about punishment) do not necessitate the establishment of their consequence for a specific individual unless the conditions are met and the impediments are removed.