VATICAN CITY (CNS) -- In an extraordinary gesture for the Year of Mercy, Pope Francis has extended to priests worldwide the authority to absolve women from the sin of abortion and has decreed the full validity during the year of the sacrament of penance celebrated by priests of the traditionalist Society of St. Pius X.

"This jubilee Year of Mercy excludes no one," the pope wrote in a letter to Archbishop Rino Fisichella, president of the Pontifical Council for the Promotion of New Evangelization, the office organizing events for the holy year, which opens Dec. 8.

Pope Francis said one of the most serious problems facing people today is a "widespread and insensitive mentality" toward the sacredness of human life.

"The tragedy of abortion is experienced by some with a superficial awareness, as if not realizing the extreme harm that such an act entails," while many other women believe that "they have no other option" but to have an abortion, the pope wrote in the letter, released Sept. 1 by the Vatican.

The pressures exerted on many women to abort lead to "an existential and moral ordeal," Pope Francis said. "I have met so many women who bear in their heart the scar of this agonizing and painful decision."

When such a woman has repented and seeks absolution in the sacrament of confession, he said, "the forgiveness of God cannot be denied."

Although Church law generally requires a priest to have special permission, called faculties, from his bishop to grant absolution to a person who has procured or helped another to procure an abortion, the pope said he decided "to concede to all priests for the jubilee year the discretion to absolve of the sin of abortion those who have procured it and who, with contrite heart, seek forgiveness for it."

Pope Francis urged priests to welcome to the sacrament women who have had an abortion, explain "the gravity of the sin committed" and indicate to them "a path of authentic conversion by which to obtain the true and generous forgiveness of the Father who renews all with his presence."

Jesuit Father Federico Lombardi, Vatican spokesman, told reporters the pope's letter "highlights the wideness of God's mercy" and is "not in any way minimizing the gravity of the sin" of abortion.

In his letter, Pope Francis also granted another exception to Church rules out of concern for "those faithful who for various reasons choose to attend churches officiated by priests" belonging to the traditionalist Society of St. Pius X. Although the society is no longer considered to be in schism and the excommunication of its bishops was lifted in 2009, questions remain over whether the sacraments they celebrate are valid and licit.