The congregation's letter also gave priests a guideline for examining their consciences concerning everything from how they celebrate Mass to how well they are living a pure, humble and generous life detached from consumerism.
Signed by the congregation's prefect, Cardinal Mauro Piacenza, and secretary, Archbishop Celso Morga Iruzubieta, the letter was dated March 26 and recently published on the congregation's website.
The letter marks the annual World Day of Prayer for the Sanctification of Priests, celebrated in many dioceses June 15 -- the feast of the Sacred Heart of Jesus.
Priests are entrusted with the task of challenging and helping people become more holy and obey God's will more fully, it said.
"We cannot be sanctified without working on the holiness of our brothers, and we cannot work on the holiness of our brothers unless we have first worked on and continue to work on our own holiness," it said.
Urging others to strive for the "ideal of perfection," it said, "does not mean that we are not aware of our personal shortcomings, or of the faults committed by some who have brought shame upon the priesthood before the world."
While not specifically mentioning clerical sex abuse, the letter said that given the worsening situation reported in the news, priests must take to heart "with greater strength and urgency" Blessed John Paul's Holy Thursday letter from a decade ago.
It said the letter condemned the perpetrators of such scandals as betraying the priesthood and casting a "shadow of suspicion" over the many good priests in the world.
Blessed John Paul called on priests "to commit ourselves more fully to the search for holiness," it said.
The letter from the Congregation for Clergy said one of the most serious problems unfolding today is people losing all sense of God's love and hope.
Traditionally, Christian nations "are no longer tempted to surrender to a general sort of atheism as they were in the past," but they risk falling victim to that brand of atheism that has "forgotten the beauty and warmth" of the Trinity of God, the Son and the Holy Spirit.
By fully embracing, adoring and living in communion with God, priests can point the way to the true face of Christ and why he is important for men and women today, it said.
"No new evangelization will really be possible unless we Christians are able to surprise and move the world again by proclaiming the nature of our God, who is love," and living as closely as possible to Christ.
In addition to the letter, the Congregation for Clergy also published Scripture passages and reflections from popes, saints and theologians, and St. Faustina Kowalska's "Prayer for the Holy Church and for Priests," which asks God to protect clergy "from the devil's traps and snares."
There was also a 20-part "Examination of Conscience for Priests" that asked priests to reflect on: how well they prepare for and lead Mass in a dignified manner; how free their lives are from vain and superficial pursuits; how central their love for Christ is in guiding them away from unchaste thoughts and acts; how charitable they are in dealing with others, especially those who sin; and how faithful their lives and teaching are to the church's Magisterium.