The observance of All Saints Day has roots in the early Roman Church as well as in the Bible itself.
On May 13, 610, Pope Boniface IV consecrated the Pantheon, a former Roman temple, giving it the new title of St. Mary and the Martyrs.
When the Pantheon was first consecrated as a Christian church, many relics of Roman martyrs were brought there from the catacombs, which helps explain its original name. Later, the title of the church was broadened to St. Mary and All the Saints, but the feast commemorating its dedication remained on May 13.
Then on November 1, 735, Pope Gregory III dedicated a chapel in St. Peter’s Basilica to a variety of saints, making it a privileged feast day in the city of Rome. Shortly thereafter Pope Gregory IV established November 1 as a holy day of obligation in the universal Church dedicated to All Saints.
All Saints Day in the Bible
While the exact name, "All Saints Day," is nowhere to be found in the Bible, the concept of celebrating a large host of holy men and women is clearly visible in the book of Revelation.
St. John the Apostle had a vision of Heaven, seeing within it a vast number of people who died and now reside in the heavenly court:
After this I looked, and behold, a great multitude which no man could number, from every nation, from all tribes and peoples and tongues, standing before the throne and before the Lamb, clothed in white robes, with palm branches in their hands, and crying out with a loud voice, “Salvation belongs to our God who sits upon the throne, and to the Lamb!” And all the angels stood round the throne and round the elders and the four living creatures, and they fell on their faces before the throne and worshiped God, saying, “Amen! Blessing and glory and wisdom and thanksgiving and honor and power and might be to our God for ever and ever! Amen.”
This reading is typically read during Mass on All Saints Day, emphasizing the fact that the liturgical celebration is rooted in the Bible.
