Now, therefore, you are no longer strangers and foreigners, but fellow citizens with the saints and members of the household of God, having been built on the foundation of the apostles and prophets, Jesus Christ Himself being the chief cornerstone, in whom the whole building, being fitted together, grows into a holy temple in the Lord, in whom you also are being built together for a dwelling place of God in the Spirit.
The Epistle of St. Paul to the Ephesians 2:19-22
The cornerstone determines the orientation of the building. Subsequent stones are set in reference to it. The Church is the guardian of the fullness of the Truth, which is Christ, her Chief Cornerstone.
Set upon the foundation of Christ and His Apostles, the Church cannot be moved from the truth. She has maintained the teachings and traditions of our spiritual fathers in spite of persecutions, heresies, schisms, revolutions and societal upheavals. In fact, she has been criticized for not changing with the times!
Since the Church has remained the same, she worships, as did the first Christians. If Saint Paul entered an Orthodox Church today, he would be at home. Because she does not latch onto the latest religious fads and fashions, the Church continues to be the household of God, and is recognizable as such.
How can the Church remain the same in a world that is constantly changing? Apostolic Succession. The Church is “built on the foundation of the apostles and prophets.” Her bishops can trace their succession back to the apostles. Has the Church ever had bad bishops or priests? Of course, but apostolic succession is more than a family tree. It is the passing on of apostolic teaching and traditions to the clergy, the monastics and the laity. No man on earth has absolute authority over the Church. She is a conciliar body living in submission to one another, and the entire body must submit to Christ her head.