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, Empress Theophano, lived a devout life. After her death, her husband built a church, intending to dedicate it to her. When he was forbidden to do so, he decided to dedicate it to "All Saints," so that if his wife were in fact one of the righteous, she would also be honored whenever the feast was celebrated.
According to tradition, it was Leo who expanded the feast from a commemoration of All Martyrs to a general commemoration of All Saints, whether martyrs or not. This Sunday marks the close of the Paschal season. To the normal Sunday services are added special scriptural readings and hymns to all the saints (known and unknown) from the Pentecostarion. The Sunday following All Saints Sunday—the second Sunday after Pentecost—is set aside as a commemoration of all locally venerated saints, such as "All Saints of America", "All Saints of Mount Athos", and so on.
When reading the lives of the saints, it is easy to discern their love for Christ. This passion for the risen Lord led them to participate in his ministry, through acts of service, rooted in kindness. Any service to the church, no matter how small or seemingly insignificant, from reading the epistle, to singing, to serving, to even vacuuming the church of lighting candles, is an active ministry, full of grace, only if it is carried out in love, sacrifice, devotion, and steadfastness. This is the life of the saint; this is a life which is well pleasing to God. Let each one of us emulate this life.
– Fr Marc Vranes