Friday the 13th is seen as a “bad luck” day mainly because two older superstitions—fear of Fridays and fear of the number 13—got blended together over time, then were amplified by religion, history, and pop culture.

Middle Ages roots (religion + numbers)

  • In Christian tradition, the Last Supper had 13 people at the table (Jesus and his 12 apostles), and Judas, who betrayed Jesus, is often described as the 13th guest.
  • Jesus was crucified on a Friday, which gave the day a long‑standing reputation as unlucky or sorrowful in Christian cultures.
  • Put together, you get a “double bad” day: an already suspicious number (13) falling on an already ominous weekday (Friday).

Why 13 was “unlucky” even earlier

  • Many cultures liked the number 12 as a symbol of completeness (12 months, 12 zodiac signs, 12 hours on a clock), so 13 felt like an extra that broke the pattern and seemed off or unstable.
  • Ancient Roman sources and later folklore link 13 with bad omens, misfortune, or even death.
  • A Norse myth tells of a feast for 12 gods in Valhalla; Loki turns up as the 13th guest and his actions lead to the death of the beloved god Balder, spreading grief through the world and giving 13 a dark reputation.

A famous historical twist: Knights Templar

  • One popular theory links the superstition to Friday, 13 October 1307, when King Philip IV of France ordered the mass arrest of the Knights Templar on charges of heresy.
  • Their leader, Jacques de Molay, was later executed; legend says he cursed his persecutors as he died, and storytellers sometimes present this as a turning point that made Friday the 13th “cursed” in people’s minds.

Is Friday the 13th really ancient?

  • Folklore scholars note that specific fear of Friday the 13th (as a combined date) seems relatively modern and may not clearly appear until the 19th century, even though Friday and 13 were each feared separately much earlier.
  • Today there’s even a term for people who are anxious about this day: paraskevidekatriaphobia, meaning fear of Friday the 13th.

Modern superstition and pop culture

  • In Western countries, many people still avoid doing important things that day—like traveling, scheduling surgeries, signing contracts, or starting new projects—because they worry it might bring bad luck.
  • Horror movies and books, especially the “Friday the 13th” film franchise with the character Jason Voorhees, turned the date into a pop‑culture symbol of something spooky, dangerous, or cursed, which keeps the superstition alive for new generations.
  • Media pieces and kids’ explainer videos now treat it as a fun, eerie topic, so even if people don’t really believe in the curse, they still play along with the vibe of the day.

So, is it actually a “bad” day?

  • There’s no solid scientific evidence that more bad things really happen on Friday the 13th than on any other day; if anything, people just remember negative events more when they fit the spooky narrative.
  • Many people treat it as just another ordinary date, and some even consider 13 a lucky number, showing that the “bad day” idea is more about culture and belief than about reality.

In short, Friday the 13th is considered a bad day because centuries of religious stories, number superstitions, dramatic historical events, and horror movies all piled up on one square of the calendar—and we’ve never really stopped telling those stories.

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Wondering why is Friday the 13th considered a bad day? Learn how religious beliefs, ancient number superstitions, the Knights Templar, and horror movies turned this date into a global spooky, trending topic.

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