Pope Benedict XVI, the head of the Roman Catholic Church, has held the Holy Thursday mass, which commemorates the last supper of Jesus Christ, in Italy's Vatican City.
The day is part of a holy week, which is a time of penance, when Christians are supposed to confess their deepest guilts and ask for forgiveness.
This year the solemn period coincides with a new wave of controversy surrounding allegations of Catholic priests involved in child sex-abuse cases.
Benedict urged priests to oppose violence as he led Thursday's ceremony.
"As priests, we are called in fellowship with Jesus Christ, to be men of peace, we are called to oppose violence and trust in the greater power of love," Benedict said.
Earlier, the pope sent a special message about priests during a weekly address to a massive crowd of the faithful on Wednesday.
"In this Year for priests, the Holy Thursday Christ mass, at which priests renew the promises made on the day of their ordination, will take on a particular significance. May priests everywhere be conformed ever more closely to Christ as heralds of his message of hope, reconciliation and peace," Benedict said.
Last month, Benedict criticised Irish bishops for grave errors of judgement in handling the priest abuse cases.
Since then, several European bishops have admitted to mishandlings and some have urged victims to consider filing criminal complaints.
Christopher Schoenborn, Austria's cardinal, made an admission among others.
"We confess, that we darkened and betrayed the name of God, which is love. Some of us spoke of the love of God, and did evil to those who most needed protection," he said.
"Again and again, my bad experiences attack me, they grow enormous in front of my eyes."
Vatican hits back
But the Vatican has also hit back at critics. Just days before the Thursday mass, a senior official of the church issued a statement defending accusations concerning Benedict's handling of sex-abuse cases.
Cardinal William Levada posted an article on the Vatican's official website, criticising the New York Times, the US newspaper, for wrongly using internal documents to find fault with the pope.
He defends the church's controversial decision not to defrock a US priest accused of molesting hundreds of handicapped boys between 1950 and 1974.
Levada is preparing to celebrate Eastern Sunday this weekend, when followers mark the resurrection of Jesus Christ.
It is seen as a time of rebirth and renewal, which is what the Vatican may be praying for this year, for the entire Catholic institution.