Francis Celebrates Mass In Havana's Revolution Square

Updated at 11:45 p.m. ET

Thousands of Cubans packed Havana's Revolution Square to celebrate Mass with Pope Francis, history's first Latin American pope, erupting in cheers as the pontiff approached in his open-sided popemobile.

Believers and non-believers waved Cuban and Vatican flags as they thronged the square, overlooked by a huge portrait of Argentine Marxist revolutionary Che Guevara. The pope in his homily steered clear of politics, but focused on the need for Christians and others to help their fellow man.

"Christians are constantly called to set aside their own wishes and desires, their pursuit of power, and to look instead to those who are most vulnerable," he told the crowd.

"We need to be careful not to be tempted by another kind of service, a 'service' which is 'self-serving,'" he said.

"Service is never ideological, for we do not serve ideas, we serve people," Francis said.

"Being a Christian entails promoting the dignity of our brothers and sisters, fighting for it, living for it," Francis told the crowd. "That is why Christians are constantly called to set aside their own wishes and desires, their pursuit of power, and to look instead to those who are most vulnerable."

He also called out the violence in Colombia and prayed for peace there amid the protracted civil war between leftist FARC rebels and the government.

"I ask you now to join with me in praying to Mary, that we may place all our concerns and hopes before the heart of Christ," the pope said. "We pray to her in a special way for those who have lost hope and find no reasons to keep fighting, and for those who suffer from injustice, abandonment and loneliness. We pray for the elderly, the infirm, children and young people, for all families experiencing difficulty, that Mary may dry their tears, comfort them with a mother's love, and restore their hope and joy. "Holy Mother, I commend to you these your sons and daughters in Cuba. May you never abandon them!"