Some buildings do not have a thirteenth floor. (Technically, they do have a thirteenth floor. They just don't number it as such). Some hotels do not have thirteen as a room number. Some people live in fear whenever the thirteenth falls on a Friday because it is a superstition that it is an unlucky day.
Here is something to think about. Everyday is the Lord's Day no matter what date it bears. There were thirteen guests at the Last supper of the Christ. There were twelve disciples, but Jesus, the Christ, made the thirteenth member at the Last Supper. Later, Judas went out and betrayed Jesus. There were twelve who were bonded, but Judas, the thirteenth was apart from them all representing rebellion, sin, and disobedience.
To chapter thirteen of the Gospel of Saint John, during of its Last supper with his disciples, Jesus declares that one of then will betray him. And after the announcement of the treason of Judas, Jesus prophesies the Peter's denial.
The thirteenth chapter of the Revelation is reserved to the Antichrist and to the Beast.
In 13th psalm, it is written: "The fool has said in his heart, There is no God."
The mystery of the Seven Churches of the Revelation presents the winner of 13 rewards on the whole.
The thirteen sons of David which were born when he was to Jerusalem. (1 Ch 3,5-9)
In the Gospel of Saint John, Jesus uses on the whole 13 comparisons or titles to designate who he is really:
I am the Bread (Jn 6,35 and 6,48 and 6,51)
I am the Light (Jn 8,12 and 9,5)
I am the Gate (Jn 10,7 and 10,9)
I am the Good Shepherd (Jn 10,11 and 10,14)
I am the Resurrection (Jn 11,25)
I am the Way (Jn 14,6)
I am the Truth (Jn 14,6)
I am the Life (Jn 14,6)
I am the Vine (Jn 15,5)
I am the King (Jn 18,37 and 19,21)
I am Son of God (Jn 10,36)
I am in the Father (Jn 14,10 and 14,11 and 14,20 and 17,8)
I am (Jn 8,24 and 8,28 and 8,58 and 13,19)