Vatican City - The relics of 21 Coptic martyrs, who were tragically slain by ISIS in Libya, are set to be honored in St. Peter’s Basilica during an ecumenical prayer service on Thursday evening, marking their inaugural feast day in the Catholic Church.

The evening vespers at the Vatican solemnly remembered the ninth anniversary of the martyrdom of these 21 Coptic Orthodox individuals, who were brutally beheaded by the Islamic State on a beach in Sirte, Libya, on Feb. 15, 2015.

Last May, Pope Francis officially recognized the 21 Coptic martyrs by adding them to the Roman Martyrology, the Church’s official catalogue of saints, during a meeting with the head of the Coptic Orthodox Church of Alexandria, Tawadros II.

Cardinal Kurt Koch, the prefect of the Vatican Dicastery for Promoting Christian Unity, led the ecumenical prayer at 5 p.m. in the Choir Chapel of St. Peter’s Basilica, with musical accompaniment provided by a Coptic choir.

Following the prayer service, a documentary titled “The 21: The Power of Faith,” produced by the Coptic Orthodox Church, was screened at the Vatican Film Library, offering a glimpse into the lives and faith of the martyrs.

The harrowing martyrdom of these 21 men, the majority hailing from Egypt, was captured on film by the Islamic State, showcasing masked militants executing the men on a Libyan beach while they were dressed in orange jumpsuits.

The authenticity of the video was later confirmed by the Egyptian government and the Coptic Orthodox Church. In October 2017, a mass grave containing the bodies of the 21 martyrs was discovered, shedding light on their fate after being kidnapped in Libya while seeking employment.

In 2018, a Coptic Orthodox church dedicated to the 21 Martyrs of Libya was inaugurated in the Egyptian village of al-Our, home to 13 of the martyred individuals.

The Coptic Orthodox Church swiftly declared the 21 Coptic Christians as martyr saints within a week of their brutal murder along the Libyan coast in 2015.

Pope Francis’ decision to include these martyrs in the Roman Martyrology in 2023 marked a significant milestone in ecumenical relations between the Catholic Church and the Coptic Orthodox Church, the largest Christian denomination in predominantly Muslim Egypt.

The Roman Martyrology serves as the official register of saints and blesseds, including martyrs, acknowledged in the liturgical practices of the Catholic Church, with its entries aligned with the Church’s calendar of feast days.

Pope Francis remarked, “These martyrs were baptized not only in water and Spirit but also in blood, a blood that serves as the seed of unity for all of Christ’s followers,” emphasizing the enduring significance of their sacrifice.

The feast day of the martyrs, known as the 21 Coptic Martyrs of Libya, is observed on Feb. 15 in both the Catholic Church and the Coptic Orthodox Church.

During Tawadros II’s visit to the Vatican last year, he presented Pope Francis with relics containing the martyrs’ blood, which will be incorporated into Thursday’s liturgy.

Tawadros expressed, “Today we present a portion of their relics, imbued with the blood shed in Christ’s name for the Church, so that they may be commemorated in the martyrology of all the churches worldwide, and recognize that 'we too' are 'surrounded by such a multitude of witnesses.'”

He added, “Given that saints are fundamental pillars of our churches, beginning with the apostles Peter, Paul, and Mark, we now inscribe in the martyrology of the churches the new martyrs who have defended the faith and testified to Christ, enduring torture without faltering and leaving us a living example in martyrdom.”