Adherence to the original Christian ecclesiology.
Communion with others who share the same doctrines, and not with those who preach heterodoxy and innovation.
Do you really need more than that? Orthodoxy offers the complete and unadulterated Truth.
To whom are you referring when you say: “…preach heterodoxy and innovation.”
Does the present-day Eastern Orthodox Church agree with what the following Eastern Orthodox saints had to say about the Petrine office? Just curious:
St. Sophronius, Patriarch of Jerusalem (d. A.D. 638)
“Teaching us all orthodoxy and destroying all heresy and driving it away from the God-protected halls of our holy Catholic Church. And together with these inspired syllables and characters, I accept all his (the pope’s) letters and teachings as proceeding from the mouth of Peter the Coryphaeus, and I kiss them and salute them and embrace them with all my soul … I recognize the latter as definitions of Peter and the former as those of Mark, and besides, all the heaven-taught teachings of all the chosen mystagogues of our Catholic Church.” – Sophronius, Mansi, xi. 461
St. Theodore the Studite of Constantinople (d. 826)
Writing to Pope Leo III:
Since to great Peter Christ our Lord gave the office of Chief Shepherd after entrusting him with the keys of the Kingdom of Heaven, to Peter or his successor must of necessity every novelty in the Catholic Church be referred. Therefore], save us, oh most divine Head of Heads, Chief Shepherd of the Church of Heaven. (Theodore, Bk. I. Ep. 23)
Sergius, Metropolitain of Cyprus (649)
Writing to Pope Theodore:
O Holy Head, Christ our God hath destined thy Apostolic See to be an
immovable foundation and a pillar of the Faith. For thou art, as the Divine Word truly saith, Peter, and on thee as a foundation-stone have the pillars of the Church been fixed. (Sergius Ep. ad Theod. lecta in Sess. ii. Concil. Lat. anno 649)