ROME -- Ukraine, like any nation under attack, has a legitimate right to self-defense and to seek justice, but great care also must be taken to defend the hearts of Ukrainians from hatred and a desire for vengeance, said the Vatican secretary of state.

When Jesus told his disciples to turn the other cheek, he was not ruling out self-defense, because "the Lord does not require unjust or impossible things," Cardinal Pietro Parolin said in a homily Nov. 17 during a Mass for peace in Ukraine.

The liturgy at Rome's Basilica of St. Mary Major marked the 30th anniversary of diplomatic relations between the Holy See and Ukraine, but it could not ignore how "nearly nine months of extensive warfare have reduced parts of the country to ruins, emptied of people, filled with debris and shrouded in darkness," the cardinal said.

Unfortunately, he said, "the reality of destruction and suffering that images and statistics put before our eyes every day feeds the temptation to give in to disappointment and distrust."

The first reading at the Mass was the prophet Isaiah's promise that the desert would become a garden and justice would be restored.

The prophet is not "naïve or a hopeless optimist," the cardinal said. Instead, he sees how God has worked in history and trusts that God will bring justice and peace.

With Andrii Yurash, Ukraine's ambassador to the Holy See, and most other members of the Vatican diplomatic corps present for the Mass, Cardinal Parolin said their prayer for peace is rooted in the same trust.

"We witness the horror of a war that has continued to sow destruction and death for so many months," he said. "We see, too, the failure of attempts to restore peace or find solutions leading to it, while blood and tears continue to flow."

"Nevertheless, we raise prayers to God for peace in Ukraine and every country suffering from war so that trust in his promises of life will not fail and that they will soon find fulfillment," the cardinal said. "Despite the failures of human wills and human efforts, we ask God to pour out his Spirit on humanity longing for peace and to be delivered from the scourge of armed conflict."

The Gospel reading at the Mass included the line where Jesus tells his disciples, "When someone strikes you on your right cheek, turn the other one to him as well."

"They are words that tear at the heart of one who has been slapped and feels the injustice of it," the cardinal said. "How can the Lord ask us not to react to aggressors? Won't this yielding to abuse legitimize it? Can peace mean surrendering to injustice, resigning ourselves in the face of aggression?"

But that is not what Jesus is saying, Cardinal Parolin said. Self-defense is legitimate.

"In asking us to turn the other cheek, in fact, he does not ask us to yield to injustice," he said.

"Violence, the abuse of power and injustice always have a twofold effect," the cardinal said. They "not only procure an external evil, but also produce an internal one, in people's hearts. Hence, while animated by the natural desire for justice, what arise are also hatred and a desire for revenge.

“And this is where the Lord teaches us to react with love. For just as it is legitimate to defend ourselves externally from those who intend to attack and overpower us, we have an even greater obligation to defend ourselves inwardly from hatred and vengeance."