Not everyone has agreed that Yom Kippur should begin with Kol Nidre. Amram Gaon, the 9th century Babylonian sage who compiled the oldest siddur still in existence, called the practice of this recitation a minhag shtut—a foolish custom—and a number of Sefardic rites, following his lead, leave the text out entirely. Kol Nidre has always been very big in Ashkenaz, but the chidren of the great commentator Rashi, who played such an important role in the formulation of Ashkenazic tradition, still felt the need to tinker with its language.

Kol Nidre is an Aramaic phrase which means far more than its literal translation, “All Vows.” This statement of annulment of vows has become such a dominant part of the Jewish religious psyche that it is commonly used to designate the whole of the Yom Kippur Eve service; its melody is so daunting that hearing the first few bars can send shivers down the spine and remind the internal, spiritual clock that the time for repentance has begun.

The 9th-century siddur, Mahzor Vitry, explains this custom in the following way: “The first time the cantor chants Kol Nidre in a very low voice, like a person who is amazed at entering the palace of the king to ask for a favor, and is afraid of coming close to the king… The second time, the cantor ought to raise his voice a little higher than the first time. The third time the cantor ought to raise his voice higher and higher, like a man who is at home and accustomed to being a member of the king’s household.” Afterwards, the people are left standing in awe, the Torah scrolls are returned, and the atmosphere is serious. The Day of Atonement has officially begun.

For all of Kol Nidre’s significance and power, its origins are shrouded in mystery. There are two “histories” regarding the prayer, one popular and the other scholarly. The popular version connects the wording of the prayer with the religious dilemma facing medieval Spanish Jews. In 15th-century Spain, at the hight of the infamous Inquisition, the Roman Catholic Church embarked on a determined hunt to seek out and punish all non-practicing Christians. In response to extreme anti-Semitism earlier that century, a sizable number of upper-class Jews chose to convert to Christianity in order to, at the very least, avoid social disdain. For a small number, their religious conversion was genuine; but for the majority, their “conversion” was in name only as they still found creative ways to practice Judaism in the privacy of their own dwellings. These Jews came to be known as “marranos” and became one of the foci of the Church’s inquistory offensive. The Kol Nidre prayer, according to this theory, was created in response to these Jews’ desire to nullify their vows of conversion. We can see the potential validity of this historical claim in a literal translation of Kol Nidre:

“All vows and oaths we take, all promises and obligations we made to God between this Yom Kippur and the last we hereby publicly retract in the event that we should forget them, and hereby declare our intention to be absolved of them.”

This legal formula may have allowed marrano Jews to rid themselves of guilt they felt when, under social and religious duress, they converted to Christianity. By setting Kol Nidre at the beginning of the first Yom Kippur service, these Jews developed a way to confront the gravest sin imaginable so that they could devote the remainder of Yom Kippur to address their other transgressions.

Scholars do not wholly refute this understanding of Kol Nidre, but they do contend that Kol Nidre has much earlier roots and probably pre-dated the marranos. According to their research, it is unclear exactly when or where the Kol Nidre legal formula was created. The wording seems to mimic other legalistic contracts of the Babylonian Jewish community of the 6th and 7th centuries. The first undoubtable citation appears in an early comprehensive siddur edited by Rav Amram in the 8th century. Over the next few centuries, the prayer became more widespread and a soulful melody became associated with it. Notably, there were some rabbis who disparaged the prayer as a superstitious attempt by Jewish mystics to nullify vows made by evil forces in the universe intent on hurting the Jewish people. These criticisms were muted by the majority of the people who cleaved to the prayer and aided its spread to other communities.

It is known that the Kol Nidre prayer gained in significance during the persecution of Jews in Spain at the time of the Inquisition. People who had been forced to convert, the Marranos, behaved outwardly like their neighbors, but inwardly they remained Jews. Once a year they used this prayer to renounce the oaths they had been forced to make forswearing their own religion in favor of Christianity.  Deep down, in their innermost souls, they remained Jewish.  The Kol Nidre was a proclamation that their vows, all their external behavior,was not really them. This prayer helped them cleanse themselves of their outer garments and reach their inner souls.

Rabbi Dessler in "Michtav Me-Eliyohu" writes that there is one part of our soul that burns like a tiny flame. That flame has the capacity to survive. No matter how hard its carrier might try to extinguish the flame, it will continue to burn.

This is what Yom Kippur and repentance are about, removing the outer garments and letting the light shine out.

Kol Nidrei prayer predates the Inquisition by at least 500 years. It would seem that the simple answer to the question is that Kol Nidrei is the opening prayer of the holiest day of the year, and as such is said with great devotion—not because of its content.

According to Kabbalah, Kol Nidrei is more than a technical vow-annulment procedure. Rather, by releasing our vows we are asking G‑d to reciprocate in kind. In the event that He has pledged not to bring the redemption just yet, in the event that He made an oath to bring harsh judgments on His people in the following year, we ask that He release these vows and instead grant us a year of happiness and redemption.

In the twelfth century, Rabbeinu Tam objected to this application of the annulment of vows due to a number of technical reasons, particularly its lack of individuality. How can you annul an individual's vows in a group ceremony which does not even list the vows, asked Rabbeinu Tam? Therefore, Rabbeinu Tam insisted on changing the text of Kol Nidrei to use a future tense so it would serve as a pre-existing clause in future vows (assuming that individuals read along quietly with the service) [Tosafot, Nedarim 23b]. This change was opposed and the original text was defended by some scholars, such as R. Asher ben Yechiel [Rosh, Yoma 8:28]. The prevailing custom is to either follow Rabbeinu Tam's modified text or to use a compromise version that includes both past and future vows.

However, and this is crucial, NO ONE claims that Kol Nidrei exempts individuals from either past or future vows that involve others. Kol Nidrei is ONLY for personal vows, as demonstrated above. Whether in business deals or in interpersonal interaction, Kol Nidrei does not in any way provide license for Jews to be deceiptful or lying.

Ideally, Kol Nidrei should begin shortly before sunset. The Torah scrolls are all removed from the Ark—it is a great mitzvah to purchase the honor of holding the first Torah scroll—and the procession of scrolls moves towards the bimah (reading table) while everyone kisses and embraces the passing Torahs.

After requesting permission, from both the heavenly and earthly courts, to “pray with the transgressors,” the cantor begins the Kol Nidrei. He chants the Kol Nidrei three times, each time on a slightly higher note. The congregation reads along with the cantor, in an undertone.

The Kol Nidrei is followed by a few brief verses and prayers and culminates with the Shehecheyanu blessing, in which we thank G‑d for “granting us life, sustaining us, and allowing us to reach this occasion.” This blessing is recited in honor of every holiday, but usually following the night’s kiddush. On Yom Kippur, because there is no kiddush, the blessing was incorporated as part of the prayers. Women and girls do not recite this blessing with the congregation—as they have already recited it after lighting the holiday candles.

The view of the early authorities

Before beseeching God for atonement of sins on Yom Kippur, it is imperative that each individual absolve himself of any vows or oaths that he may have made and subsequently violated. The severity of violating a vow or an oath is such that it may block or interfere with the entire atonement process[4]. Consequently, one who is aware of any violations of oaths or vows that he may have committed is strongly urged to petition a Jewish court in order to find a way out of his self-imposed obligations. Indeed, it has become customary that already on erev Rosh Hashanah, all males petition a beis din for hataras nedarim.

But not everyone is familiar with the procedure of hataras nedarim, and not everyone who has violated a neder or a shevuah realizes that he has done so. To avert and to solve this problem, Kol Nidrei was instituted. Kol Nidrei declares that in case an individual made a vow or an oath during the past year and somehow forgot and violated it inadvertently, he now regrets his hasty pronouncement. In effect he tells the “court” – comprised of the chazan and two congregational leaders – that had he realized the gravity and severity of violating an oath, he would never have uttered it in the first place. He thus begs for forgiveness and understanding[5]. This explanation of Kol Nidrei, put forth by many of the early authorities and endorsed by the Rosh, fits nicely with the traditional text of Kol Nidrei, which reads, “from the last Yom Kippur until this Yom Kippur,” since we are focusing on vows and oaths which were undertaken during the past year[6].

The view of Rabbeinu Tam

Other authorities – led by Rabbeinu Tam – strongly object to this interpretation of Kol Nidrei. Basing their opinion on various halachic principles, they question if it is legally valid to perform hataras nedarim in this manner. In their view, Kol Nidrei was instituted to deal with the problem of unfulfilled vows, but from a different angle: Instead of annulling existing vows and oaths, Kol Nidrei serves as a declaration rendering invalid all future vows and oaths which may be uttered without due forethought – “null and void, without power and without standing[7].” Accordingly, the text was amended to read “from this Yom Kippur until the next Yom Kippur,” since we are referring to what may happen in the future, not to what has already happened in the past.