Pope Francis has begun his week-long visit to three of the poorest countries in South America, arriving on Sunday afternoon in Ecuador where he was greeted by a youth orchestra and a long line of Catholic crowd from the airport to the capital Quinto.

Millions are expected to hear a mass led by the Argentinian pontiff, who is expected to bring his message of hope, concern for the poor, and care for the environment in Ecuador before proceeding to Bolivia and Paraguay.

"Dear friends, I begin my visit filled with excitement and hope for the days ahead," the Pope told the crowd waiting for his arrival at the Mariscal Sucre International Airport, according to CNN.

After receiving a warm welcome from Ecuadorian President Rafael Correa, Francis asked Catholic believers in Ecuador never to lose their ability to "thank God for what He has done and is doing for you."

"May you never lose the ability to protect what is small and simple, to care for your children and your elderly, to have confidence in the young, and to be constantly struck by the nobility of your people and the singular beauty of your country," he said.

Pope Francis will have a seven-day itinerary, visiting three Latin American countries for the first time since becoming the head of the Roman Catholic Church in 2013.

However, the Vatican said the Pope will not be visiting his home country, Argentina. "The decision not to visit the continent's larger nations reflected the Pope's interest in the peripheries," BBC quoted officials from the Vatican.

Rev. Gustavo Morello, a Jesuit from Argentina and a professor of sociology at Boston College, said Ecuador, Bolivia, and Paraguay are the poorest and forgotten countries of Latin America which Francis hopes to change.

Citing religious experts, the CNN reported that the Pope hopes to "breathe new life into a Catholic Church" that is suffering through a continent-wide decline of members who have been fleeing the religion for other faiths.

According to a study by Pew Research Center, 425 million of the 1.2 billion Catholics in the world live in Latin America.

"We can find in the Gospel a key to meeting contemporary challenges, respecting differences, fostering dialogue and full participation, so that the growth in progress and development already registered will ensure a better future for everyone," Francis said.

"For centuries that faith has shaped the identity of this people and borne much good fruit," he added, citing saints who were born out of the rich Catholic heritage in Ecuador, according to Catholic News Agency.

St. Mariana de Jesus, St. Miguel Febres, and St. Narcisa de Jesús, as well as Blessed Mercedes de Jesús Molina, who were beatified in 1985 during St. John Paul II's visit, are the saints hailing from Ecuador.

"These, and others like them, lived their faith with intensity and enthusiasm, and by their works of mercy they contributed in a variety of ways to improving the Ecuadorian society of their day," the pontiff said, according to CNA.