"Now we command you, brethren, in the name of our Lord Jesus Christ, that ye withdraw yourselves from every brother that walketh disorderly, and not after the tradition which he received of us." - 2 Thessalonians 3:6

Every Orthodox Bishop is a successor of Saint Peter, if he faithfully upholds Holy Tradition.

~ ~ ~ The Heresy of Papism ~ ~ ~

On this Rock
3And did all eat the same spiritual meat; 4And did all drink the same spiritual drink: for they drank of that spiritual Rock that followed them: and that Rock πέτρα (petra) was Christ Χριστός (Christos)' - 1 Corinthians 10:3, 4.
The Rock is always Christ.
In both the New and Old Testaments. There is no other Rock. Even when one man, the prophet Moses, led the entire nation of Israel through the wilderness for 40 years, the Rock was Christ.

Matthew 16:18: AND ON THIS, THE ROCK, I WILL BUILD MY CHURCH
καὶ ἐπὶ ταύτῃ, τῇ πέτρᾳ
and on this, the rock
ταύτῃ 'this' is in the feminine gender - so it cannot be referring to Peter.

In Matthew 16_18, the word 'this' refers to Saint Peter's confession of Jesus as the Son of God which the Holy Apostle just made in Matthew 16:16.

The Rock = Christ - "For other foundation can no man lay than that is laid, which is Jesus Christ" - 1 Corinthians 3:11

"And whosoever shall fall on this stone shall be broken: but on whomsoever it shall fall, it will grind him to powder." - Matthew 21:44

The Rock in scriptures (both the OT and NT) is always Christ. There is no other Rock, no other Foundation, no other Head. We (along with the Apostles and Saints) also share in the glory and reign of Christ - but only in a derivative sense.

In Matthew 16_18, the expression 'on this rock' is referring to the confession that Peter just made regarding Christ as the Son of God. Only in a derivative sense does it apply to Saint Peter, and in this derivative sense it applies equally to all Apostles and Orthodox Bishops. Every Orthodox Christian who upholds firmly the Orthodox Faith is also rock. Conversely, any who dare to depart from the fullness of the Orthodox Faith, even a bishop, is not a rock but a stubble carried in the wind having drifted away from the True Rock Who is The Lord God.

"But of these who are accounted (δοκούντων) to be something, (whatsoever they were, it maketh no matter to me: God accepteth no man's person) for they who are accounted (δοκούντων) something in conference added nothing" - Galatians 2:6

"And when James, Peter, and John, who are accounted (δοκούντων) to be pillars, perceived the grace that was given unto me, they gave to me and Barnabas the right hands of fellowship; that we should go unto the heathen, and they unto the circumcision" - Galatians 2:9

"But Jesus called them to him, and saith unto them, Ye know that they which are accounted (δοκούντων) to rule over the Gentiles exercise lordship over them; and their great ones exercise authority upon them. But so shall it NOT BE among ye" - Mark 10: 42, 43. The apostles are commanded by the Lord not to set any one of them above the others.

There was no PAPAL SUPREMACY or PAPAL INFALLIBILITY in the days of the Apostles:

"But when Peter was come to Antioch, I withstood him to the face, because he was to be blamed" - Galatians 2:11

Is the pope greater than Saint Peter?

Christ specifically forbids the apostles from exercising authority over the other apostles, or considering oneself a teacher over the other apostles - "for you have One Instructor, The Christ." Is the pope greater than the Lord?

In the case of the heresy of papism (papal supremacy, papal infallibiblity) this is indeed the case. Papism has recognized in the person of the pope attribute which are exclusive to The Lord (infallibility, supremacy above the hierarchy) and thus the papacy has become a forerunner of the antichrist. The prefix anti in the Greek means primarily "instead of" or "in the place of" not merely opposition, though in the case of the papacy it is of the spirit of the antichrist in both contexts - the papacy has established itself in the place of The Lord and has set itself in opposition against The Lord.

"Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God" - 2 Thessalonians 2:4

No person but The Lord Who alone can proclaim to man that 'I am (EGO EIMI) the Truth' possesses infallibility.

"Not may it be: let be however God be true, but every man a liar; as it is written, That thou mightest be justified in thy words, and mightest overcome when thou art judged." - Romans 3:4

"Then Peter and the other Apostles answered and said, We ought to obey God rather than men" - Acts 5:29