In 1010, the parish priest of Ivorra, Bernat Oliver, was celebrating mass in the St. Mary's Sanctuary of Ivorra, situated in no more than a kilometre of the village. At the moment of the consacration he doubted about Jesus Christ's presence in the Eucharist and then the prodigy is produced: the wine which the chalice contained becomes blood and begins pouring on the altar cloth and the floor. By the astonishment of those presents, some women who took up the door of the hermitage, enter and with the tows in their hands dry the blood of the chalice pouring.

Saint Ermengol, who had been Bishop of Urgell from 1010 to 1035, stayed in Guissona and was informed of what had happened in Ivorra. Right after that he presented himself at Ivorra, he collected the chalice and the altar cloth stained with blood and he took them to Rome. The Pope Sergius IV, after hearing the narration of the Bishop Ermengol, he signed a Pontifical Bull certifying that it was a true miracle, he kept the chalice and gave a number of relics to Ivorra, conceding to the village provileges for the Confraternity of St. Mary's of Ivorra that St. Ermengol had founded. These relics, together with a part of the altar cloth stained with blood, and the Pontifical document, were placed under the high altar of the parish church of Ivorra dedicated to St. Cugat, inaugurated the year 1055 by the Bishop Guillem of Urgell.

In the Confraternity of St. Mary's of Ivorra, a parchment of the 14th. century is conserved with a copy of the constitutions of St. Ermengol. It was like a beneficient association in which twelve heads of a family were, at least, inscribed and had the privilege to select their captains and administrators. A structure incipiently democratic to preserve probably the Confraternity of the feudal lords of the epoch. Their finalities were to help themselves mutually so that any member of the Confraternity and his family which were deteriorated by misfortunes or long illnesses and nothing to live on could be provided with possessions of the Confraternity; any member of the guild, who might fall ill and with nobody to be attended and watched, was washed by another member of the guild assigned by the corresponding captain; marriage portion was given to the daughters of the members of the guild who hadn't possessions to marry and other altruistic conditions such as those mencioned.

At the end of the 14th. century, in some works carried out by the parish church, the relics appeared and the document of the Pope Sergius IV. Having made the fact known to the Pope's ambassador in Catalonia, he made this be analysed by the Abbat of the Monastery of Cardona, who determined its authenticity. Since then, the renown, that the miracle of the Holy Doubt has, extends all over the Crown of Aragó and the Princedom of Catalonia, so extensively that the King Alfons el Magnanim published a document authorising the Confraternity of Ivorra to go all over the Kindom to preach the miracle and to collect money to build a wortny reliquary of the relics.

At present the relics are conserved inside the Gothic Reliquary of the year 1426, fruit of that popular collection. It contains, a part from a piece of the altar cloth stained with blood, the other relics given by the Pope Sergius IV to St. Ermengol: a hair of the Virgin Mary, a thorn of the Crown of Jesus, a fragment of stone of the sepulchre of the Lord and other relics of Saints.

The church where the Holy Doubt occurred remained small with the numerous people who wend on peregrination. In its place the the present Sanctuary inaugurated the year 1663 was constructed, even though the façade dates from 1762. The Baroque Altar which stayed there was destroyed during the Spanish Civil War in 1936. From the primitive church a Gothic Altarpiece of the 15th. century is registered in the Diocesan Museum of Solsona. The Sanctuary has been object, in the last years of the 20th century, of a restauration which has saved it of its fall. The building consists of, besides the church, other dependencies that anciently served to welcome the pilgrims.

At present three feasts are celebrated: the principal feast of the Holy Doubt the first Sunday after Easter or "Sunday after Easter", with a congregation in which all the villages of the surroundings participate; the feast of St. Mary's of Ivorra on the 15th of August; and the feast of Candlemas on the 2th of February.