The Sunday following Pentecost is dedicated to all saints, both those who are known to us (those who have "stood out" the most and have been glorified and canonized by the Church), and those who are known only to God (we can easily say that these are most of the saints). There have been saints at all times, and they have come from every corner of the earth. They were apostles, martyrs, prophets, hierarchs, monastics, and righteous, yet all were perfected by the same Holy Spirit.
The descent of the Holy Spirit makes it possible for us to rise above our fallen state and to attain sainthood, thereby fulfilling God’s directive to “be holy, for I am Holy” (Leviticus 11:44, 1 Peter 1:16). Therefore, it is fitting to commemorate all saints on the first Sunday after Pentecost.
This feast may have originated at an early date, perhaps as a celebration of all martyrs, then it was broadened to include all men and women who had borne witness to Christ by their virtuous lives, even if they did not shed their blood for Him.
In the Orthodox Christian Church the saints are ordered into six ranks, which are based on their importance to the Church. The Apostles are listed first, because they were the first to spread the Gospel throughout the world. The Martyrs come next because of their example of courage in professing their faith before the enemies and persecutors of the Church, which encouraged other Christians to remain faithful to Christ, even unto death, and the non-Christians to convert to the True Faith. Although they come first chronologically, the Prophets are listed after the Apostles and Martyrs. This is because the Old Testament Prophets saw only the shadows of things to come, whereas the Apostles and Martyrs experienced them firsthand. The New Testament also takes precedence over the Old Testament. The holy Hierarchs comprise the fourth category. They are the leaders of their flocks, teaching them by their word and their example. The Monastic saints are those who withdrew from this world to live in monasteries, or in seclusion. They did not do this out of hatred for the world, but in order to devote themselves to unceasing prayer, and to do battle against the power of the demons. The last category, the Righteous, are those who attained holiness of life while living “in the world.” Examples include Abraham and his wife Sarah, Job, Joachim and Anna, Joseph the Betrothed, Juliana of Lazarevo, and others.
The feast of all saints achieved great prominence in the ninth century, in the reign of the Byzantine Emperor Leo VI the Wise (886-911). His wife, the Holy Empress Theophano lived in the world, but was not attached to worldly things. She was a great benefactor to the poor, and was generous to the monasteries. She was a true mother to her subjects, caring for widows and orphans, and consoling the sorrowful.
Even before the death of Saint Theophano in 893/894, her husband started to build a church, intending to dedicate it to Theophano, but she forbade him to do so. It was this emperor who decreed that the Sunday after Pentecost be dedicated to all saints. Believing that his wife was one of the righteous, he knew that she would also be honored whenever the Feast of all saints was celebrated.
As with fine porphyry and royal purple,
Your church has been adorned with Your martyrs’ blood shed throughout all the world.
She cries to You, O Christ God:
Send down Your compassion on Your people,
Grant peace to Your habitation, and great mercy to our souls.
The universe offers You the God-bearing martyrs,
as the first fruits of creation, O Lord and Creator.
Through the Theotokos, and their prayers establish Your Church in peace.
Through the prayers of all the saints, O Lord Jesus Christ, have mercy on us and save us. Amen.