According to biblical tradition, 13 guests attended the Last Supper, held on Maundy Thursday, including Jesus and his 12 apostles (one of whom, Judas, betrayed him). The next day, of course, was Good Friday, the day of Jesus’ crucifixion.
The seating arrangement at the Last Supper is believed to have given rise to a longstanding Christian superstition that having 13 guests at a table was a bad omen—specifically, that it was courting death.
Though Friday’s negative associations are weaker, some have suggested they also have roots in Christian tradition: Just as Jesus was crucified on a Friday, Friday was also said to be the day Eve gave Adam the fateful apple from the Tree of Knowledge, as well as the day Cain killed his brother, Abel.
Info source: https://www.history.co.uk/
Before we prove to you the auspiciousness, let’s talk about the possible (but unproven) origins of triskaidekaphobia. It might have to do with the fact that Judas Iscariot was one of the 13 people at Jesus’s last supper. Or maybe because the end of the Mayan calendar’s 13th baktun calendar cycle was supposed to herald the apocalypse.
But for Jews it is not like that. As blogger Joshua Hammerman points out, there are a bunch of reasons why not. Just think: What is the age of a bar mitzvah boy? How many months are there in the Hebrew lunar calendar? And don’t forget the 13 attributes of God laid out in Exodus to explain why God forgave us for that whole golden calf episode.
Still unconvinced? Consider that Maimonides aka the Rambam, formulated 13 principles of faith. And then there’s this clincher: When Israel was established in 1948, the first provisional government had 13 members.