All Saints Day
https://www.catholic.com/encyclopedia/all-saints
All Souls Day (Dia de los Muertos):
https://www.catholic.com/qa/churchs-stance-on-dia-de-los-muertos
Celebration of Samhain
(what I did find dates the beginning of the festival to the ninth century, thus post-dating the arrival of Christianity to the British Isles)
https://en.wikipedia.org/wiki/Samhain
What are the origins of All Saints Day and All Souls Day?
Are these linked with paganism and Halloween? – Catholic Straight Answers
All Saints
Catholic Answers Encyclopedia
https://www.catholic.com/encyclopedia/all-saints
Whom We Honor on All Saints Day | Catholic Answers Q&A
https://www.catholic.com/qa/whom-we-honor-on-all-saints-day
All Souls
https://www.ewtn.com/catholicism/seasons-and-feast-days/all-souls-20378
All Souls’ Day | Catholic Answers Encyclopedia
https://www.catholic.com/encyclopedia/all-souls-day
What’s the Point of Halloween? | Catholic Answers Magazine
https://www.catholic.com/magazine/online-edition/whats-the-point-of-all-saints-day
What is the significance of All Saints Day?
National Shrine of the Immaculate Conception
All Saints’ Day – Saints & Angels – Catholic Online
https://www.catholic.org/saints/allsaints/
Halloween and the Triduum of Death
There used to be a liturgical trifecta for the dead at this time of year: All Hallows’ Eve, All Saints, and All Souls
https://www.catholic.com/magazine/online-edition/halloween-and-the-triduum-of-death
Halloween perverted by the secular world, witchcraft, the occult. Should Catholics just ignore it?
SATANIC RITUALS DURING HALLOWEEN
Sacrifices during Halloween
“History of All Hallows’s Eve”
https://www.catholicculture.org/culture/liturgicalyear/overviews/months/10_2.cfm
“The Solemnity of All Saints is celebrated on November 1. It is a solemnity, a holyday of obligation and the day that the Church honors all of God’s saints, even those who have not been canonized by the Church. It is a family day of celebration—we celebrate the memory of those family members (sharing with us in the Mystical Body, the doctrine of the Communion of Saints) now sharing eternal happiness in the presence of God. We rejoice that they have reached their eternal goal and ask their prayers on our behalf so that we, too, may join them in heaven and praise God through all eternity. The honoring of all Christian martyrs of the Faith was originally celebrated on May 13, the date established by the fourth century. Pope Boniface IV in 615 established it as the “Feast of All Martyrs” commemorating the dedication of the Pantheon, an ancient Roman temple, into a Christian church dedicated to the Blessed Virgin Mary and all the martyrs. By 741, the feast included not only martyrs, but all the saints in heaven as well, with the title changing to “Feast of All Saints” by 840. In 844, Pope Gregory IV transferred the feast to November 1st, timing it around the harvests to be able to provide food for the pilgrims. Some scholars believe this was to substitute a feast for the pagan celebrations during that time of year. Pope Sixtus IV in 1484 established November 1 as a holyday of obligation and gave it both a vigil (known today as “All Hallows’ Eve” or “Hallowe’en”) and an eight-day period or octave to celebrate the feast. This feast is marked with liturgical observances that have changed over the centuries. By 1955, the octave and vigil of All Saints were abrogated. Instead of a separate vigil on the calendar, the celebration begins the evening before, as mentioned in The General Norms for the Liturgical Year and the Calendar“”
HALLOWEEN

