Pope Francis' four-hour Saturday prayer vigil is part of a "major peace initiative" that is receiving a favorable reaction across religious lines, a leading Vatican communications figure has said.

"Pope Francis wants to keep this issue alive to make sure everything possible could be done to put an end to the violence, and not to increase it," Greg Burke, senior communications adviser to the Holy See's Secretariat of State, said Sept. 7.

"The response has been really positive, not only from Catholics, but from other Christians and non-Christians as well."

The prayer vigil drew an estimated 100,000 people to St. Peter's Square on Saturday evening. They prayed the Rosary with Pope Francis in the presence of the famous Marian icon "Salus Populi Romani," the Protectress of the Roman People. Those gathered also prayed in adoration of the Blessed Sacrament.

Pope Francis' remarks at the vigil strongly condemned war.

"We bring about the rebirth of Cain in every act of violence and every war. All of us," he said. "Even today we raise our hand against our brother. Even today we let ourselves be guided by idols, by selfishness, by our own interests."

"Can we learn once again to walk and live in the ways of peace?" the Pope asked. "Yes, it is possible for everyone!"

Catholics and others held thousands of similar prayer events around the world in response to the Pope's Sept. 1 call for a vigil for "the whole Church."

"There are so many conflicts in this world which cause me great suffering and worry, but in these days my heart is deeply wounded in particular by what is happening in Syria and anguished by the dramatic developments which are looming," Pope Francis said in St. Peter's Square on Sept. 1.

Burke said that Pope Francis' numerous actions show how important peace is to him.

"If you look at the Pope's tweets, his letter to Putin and the G-20, and the diplomatic activity in the course of the week, this has been a major peace initiative on the part of Pope Francis," Burke said before the vigil. "Today he's asking everyone to join in by praying. The Pope will be praying not only for Syria but for peace in the Middle East and the entire world."

The U.S. government has threatened military strikes on Syrian government forces, which it blames for a massive chemical weapons attack that killed over 1,400 people. The Syrian conflict between government and rebel forces has killed more than 100,000 since March 2011.

In a Sept. 4 letter to Russian president Vladimir Putin, the host of the G20 summit in St. Petersburg, Russia, Pope Francis urged world leaders to "overcome the conflicting positions" and "lay aside the futile pursuit of a military solution."

He said that "one-sided interests" have "hindered the search for a solution that would have avoided the senseless massacre now unfolding."