Answer: Some claim the concept of ill luck is connected to the date of Friday, October 13, 1307, when “The Poor Fellow-Soldiers of Christ and of the Temple of Solomon” also commonly known “Knights Templar” were arrested at dawn on orders of King Phillip IV (Phillip le Bel) in France on charges of heresy. History also has revealed this French king owed the Order of knights money.
However, the idea about the arrest of the Templars only came to the forefront of public attention with the publishing of Dan Brown’s The Da Vinci Code, 2003 (interesting fiction book; fun movie with Tom Hanks).
Prior to that book, most folklorists drew the origin of the belief that Friday was considered an ill-omened day from the religious belief that Jesus Christ died on a Friday. Indeed, the Catholic Church eventually termed the Friday before Easter as "Good Friday" to emphasize the death of Christ was the GOOD and necessary sacrifice for the Redemption of all Christians.
Still, ordinary Fridays remained unlucky days in popular superstition. Friday was considered a bad day to close a business deal or begin a trip. It's also considered unlucky to have 13 people sitting at a dinner party, because Judas Iscariot--who betrayed Christ--was the 13th person at the Last Supper. As you can see this “paraskevidekatriaphobia”--which is an extreme and irrational fear of the day of Friday the 13th--got spread through Western Civilization largely due to Christian folklore.
The word, Paraskevi, is Greek for “Friday”. This phobia is related to “triskaidekaphobia,” which means "an extreme and irrational fear of the number 13," got spread in Western Civilization largely due to Christian folklore--and has little to do with Neo-Pagan beliefs.
STILL worried? Light a small green candle or yellow golden candle to the Goddess Freya whose day is Friday. Yes, the word for “Friday” Freyesdaeg in Anglo-Saxon, means “Freya’s Day”.
Freya is the beautiful, blue-eyed, yellow-haired Goddess of love, beauty, and fertility. She is one of the Vanir. Share a glass of mead or sweet wine with her. Ask for her blessing and for golden luck on Friday the Thirteenth—or on any Friday for that matter.
Quick note: The name of this day in German is Freitag. Another modern name of this phobia about Friday the !3th is “Friggatriskaidekaphobia” and it is drawn from the name of the Norse Goddess Frigg, who is also attached to Friday—so maybe you could pour a glass of mead for her too.
Copyright Friday, September 13, 2019, Myth Woodling
Perché l'acqua alla luce della luna il 13 di venerdì dovrebbe essere una sfortuna? È il numero 17 che è malo.
(Translation: Why should Moon Water made on Friday the 13th be bad fortune? It is the number 17 that is ill-omened.)