Klingon religion refers to the varied ritual practices and spiritual beliefs of the Klingon race.
Sacred texts[]
Texts such as the Paq'batlh ("The Book of Honor"), and the Sacred Scrolls of the Kuvah'magh formed a basis for Klingon belief. (VOY: "Barge of the Dead") One important religious author was Klavek. (VOY: "Prophecy") Additionally, some information was passed down orally by High Clerics. (TNG: "Rightful Heir")
Sacred objects[]
A number of things could be regarded as sacred or holy in Klingon religion. Nay'Poq was considered a holy month. (VOY: "Prophecy")
The planet Boreth was regarded as the most sacred site in the Klingon Empire. (DIS: "Through the Valley of Shadows") The Caves of No'Mat were a significant pilgrimage site. (TNG: "Rightful Heir") There was also a sacred vault on Qo'noS. (TNG: "Rightful Heir")
Sacred objects included adanji incense, the Beacon of Kahless, the Knife of Kirom, kor'tova candles, the Shroud of Kahless, the Shroud of the Sword, the Sword of Kahless, and the Torch of G'boj. It was customary to display images of Kahless in one's home. (VOY: "Prophecy")
Some ships, such as those commanded by T'Kuvma or Kohlar were considered holy.
Beliefs[]
Klingon beliefs might be described as polytheistic, in that a number of supernatural figures were recognized. Nevertheless, imperial cults centered on the historic figures of Kahless the Unforgettable or his rival Molor. (DIS: "Will You Take My Hand?") Charismatic or messianic figures, such as the Kuvah'magh, and T'Kuvma, also had devotees. (VOY: "Day of Honor"; DIS: "The Vulcan Hello")
Creation[]
The mythological place of creation was called Qui'Tu. (Star Trek V: The Final Frontier)
Gods were said to have forged the heart of the first Klingon, Kortar, out of fire and steel. Seeing his loneliness, they forged a mate for him. (DS9: "You Are Cordially Invited") Because they were "more trouble than they were worth”, the two Klingons “destroyed the gods who created them and turned the heavens to ashes”. (DS9: "Homefront") As punishment, Kortar was condemned to helm the Barge of the Dead. (VOY: "Barge of the Dead")
A version of this creation myth was told during the traditional Klingon wedding ceremony. (DS9: "You Are Cordially Invited")
Afterlife[]
Gre'thor[]
The dishonored dead were ferried across the River of Blood, past the Kos'Karii, aboard the Barge of the Dead. Their destination was Gre'thor, where they would be tortured by a creature known as Fek'lhr. (VOY: "Barge of the Dead")
Sto-vo-kor[]
The honored dead hoped to arrive in Sto-vo-kor, where they would be greeted by the legendary hero Kahless the Unforgettable and join the Black Fleet. (VOY: "Day of Honor"; DIS: "The Vulcan Hello")
Should a noble warrior die in a manner that might not merit a place in Sto-vo-kor, such as being assassinated in a surprise attack, he may still earn a place, if others dedicated a great battle to his name, thus showing that he had earned respect among the living. (TNG: "Heart of Glory", "Rightful Heir"; VOY: "Barge of the Dead"; DS9: "Shadows and Symbols")
When going into battle, Klingon warriors often sang the traditional warriors' anthem, which was essentially an invocation to Kahless and a pledge to win a good death in battle. (DS9: "Soldiers of the Empire")
Cavern of Despair[]
The Cavern of Despair was the home for those who had died and been forgotten. The dead could not rest in Sto-vo-kor unless the living honored their memories. Consequently, it was a common practice to recite a plea for Kahless to lift family and friends out of the Cavern of Despair. (VOY: "Prophecy")
Burial practices[]
At least until the 23rd century, some Klingons buried their dead in sarcophagi. (DIS: "The Vulcan Hello") However, by the 24th century, many Klingons tended to believe that when a Klingon died, the spirit was considered to have exited the body, leaving behind a worthless shell to be disposed of. (VOY: "Emanations")
In the Klingon death ritual, it was traditional for those on hand to howl into the sky, as a warning to the afterlife that a Klingon warrior was about to arrive. (TNG: "Heart of Glory"; DS9: "Tears of the Prophets") In some cases, a funeral dirge was sung in memory of the deceased, or friends sat with the body to protect it from predators, a practice known as ak'voh. (DS9: "The Ship")
Prophecy[]
The Story of the Promise indicated that Kahless was to reappear in the lava caves on the planet of Boreth. (TNG: "Rightful Heir")
It was foretold that the discovery of the lost Sword of Kahless would one day unite the Klingon people. (DS9: "The Sword of Kahless")
Sacred scrolls foretold the arrival of the Kuvah'magh ("The Savior of the People"). (VOY: "Prophecy")
Formal worship[]
Most Klingons in the 23rd and 24th centuries worshipped Kahless. This was overseen by clerics known as the Followers of Kahless or Guardians. (TNG: "Rightful Heir")
The Day of Honor was a major Klingon holiday calling for personal reflection. (VOY: "Day of Honor") The Kot'baval Festival was an observance commemorating Kahless' defeat of Molor. (TNG: "Firstborn")
A minority of Klingons continued to identify as Followers of Molor, a sworn enemy of Kahless, in the 23rd century. (DIS: "Will You Take My Hand?")