“Let us extol Peter and Paul, those two great luminaries of the Church, for they shine brighter than the sun in the firmament of faith” (Stichera for Vespers).
In the Orthodox Church, the Apostle Peter iss the first among the Apostles because of his authority, while Paul is equally first among the Apostles because of his apostolic labor. In icons they are depicted together as pillars of the Church of Christ. Their primary title together is therefore "Foremost of the Apostles".
Peter and Paul gave living testimony to their faith by their glorious martyrdom during the first persecution of Christians by Emperor Nero, which lasted from 64 to 67 AD. Bishop Eusebius of Ceasarea (d. 339), the first Christian historian, wrote:
“Publicly announcing himself as the first among the enemies of God, he [Nero] was led on to the slaughter of the Apostles. It is recorded that in his days Paul was beheaded in the city of Rome and that Peter, also, was crucified. This story is supported by the fact that the names of Peter and Paul are preserved in the cemeteries of that place even to the present day ... For if you would go to the Vatican, or to the Ostian Way, you would find their trophies [monuments]” (cf. Eusebius, Ecclesiastical History II, 25) .
The first to mention the martyrdom of Peter and Paul in Rome was St. Clement of Rome (88-97) in his Letter to the Corinthians. The second century writer, Tertullian, mentions that Peter was “crucified” on Vatican Hill, while Paul was ”beheaded” and buried on the Ostian Way “outside the walls” (cf. On the Prescription, 36). The same Eusebius quotes Origen of Alexandria (d. 253), as saying: “Peter …, having at last come to Rome, was crucified head downwards, for he had requested that he might suffer in this way” (Eccles. Hist. III, 1). Since that time, the tradition of the Roman martyrdom of both of these Apostles has been constant and unanimous. It has also been confirmed by recent excavations.
The tomb of St. Peter on Vatican Hill and the tomb of St. Paul on the Ostian Way “outside-the-walls” soon became places of public veneration. Constantine the Great (d. 337) built a magnificent basilica over the tomb of St. Peter in the Vatican, and a modest church over the tomb of St. Paul.
By the middle of the fourth century the Roman Church began to celebrate the Feast of Sts. Peter and Paul on June 29 with “great solemnity and festivities.” The Emperors Valentinian II (d. 392) and Theodosius the Great (d. 395) rebuilt the modest church of St. Paul to the fitting grandeur of a basilica.
In a short period of time, the pilgrims had extended the public veneration of Sts. Peter and Paul to all the corners of the Roman Empire, in the West as well as in the East. Generally, the Eastern Churches celebrated the memory of Sts. Peter and Paul on December 28, immediately following the commemoration of St. Stephen the Protomartyr (December 27) . At the beginning of the sixth century, when the Church of Constantinople started to celebrate the memory of Sts. Peter and Paul with great solemnity, the East also accepted the Roman date of celebration. Since then, the Eastern Churches have been celebrating the Feast of the Holy, Glorious and Illustrious Foremost Apostles Peter and Paul together with the West, on June 29.
The following day, June 30, the Orthodox Church solemnly commemorates all Twelve Apostles together (Synaxis).
The importance of the commemoration of the Holy Apostles Sts. Peter and Paul in the Orthodox Church is emphasized by a certain period of fasting, known as the Apostles Fast, or the Fast of the Apostles. The Apostles Fast is a very ancient fast, and there are some indications that it was already observed at the end of the fourth century, in connection with Pentecost:
"After you have kept the Feast of Pentecost, keep one week more festive, and after that, fast. It is reasonable to rejoice for the gifts of God, but after some time of relaxation, you should fast again" (cf. The Apostolic Constitutions V, 20).
This is confirmed by the great Orthodox liturgist, Archbishop Symeon of Thessaloniki (d. 1429), who, in his “Answers” to Bishop Gabriel of Pentapolis, wrote: “After the descent of the Holy Spirit (Pentecost) we, according to the Apostolic Constitutions [ascribed to St. Clement of Rome], still rejoice for one week, and then, we start fasting again, as not to be spoiled by excessive pleasure. At the same time, by our fasting, we honor the Apostles who taught us how to fast” (P.G., vol. 155, col. 901).
Beginning in the sixth century, through the influence of the monasteries, a stricter and more regulated way of fasting in honor of the Holy Apostles Peter and Paul was introduced. This time also became a period of preparation for the reception of the Holy Mysteries. The Fathers insisted that the faithful receive Holy Communion at least four times a year, namely: 1) Easter [Pascha], 2) Feast of the Apostles, 3) Feast of the Dormition of the Theotokos, and 4) Christmas [Nativity]. Hence, the reason why the Orthodox Church has four fasting seasons. These serve as suitable times of preparation for the reception of Holy Communion. These venerable fasting traditions give us an opportunity to prepare ourselves, by prayer and fasting, for our spiritual renewal and for the proper reception of Holy Communion.