"Love of God and neighbor is the greatest commandment of the Gospel," he said, adding that today the Lord asks us to respond to the call to love by "putting God at the center of our lives and dedicating ourselves to the service of our brothers, especially those most in need of support and consolation."
Noting how difficult it can be to love at times, the Pope said that "if there is an attitude that is never easy, is never a given even for the Christian community, it's knowing how to love, to love one another well based on the example of the Lord and with his grace."
"At times conflict, pride, envy and division leave their mark even on the beautiful face of the Church," he said, explaining that a Christian community must live in the charity of Christ.
However, it is exactly there where the devil comes and tries to fool us, Francis said, adding that those who allow themselves to fall for his delusions are "the most spiritually weak people."
Even for Christians, knowing how to love is never a given "once and for all," he said. Rather, we must begin again each day and put in the effort so that the love we have for the brothers and sisters we meet "becomes mature and purified by those limits or sins that leave it partial, selfish, sterile and unfaithful."
"Every day we must learn the art of loving, every day we must follow with patience the school of Christ, with the help of his Spirit," he said, and led pilgrims in praying the traditional Regina Coeli prayer, recited during Easter instead of the Angelus.
After, Francis noted that on May 24, the same day as his meeting with U.S. President Donald Trump, Catholics in China will celebrate the feast of Mary, Help of Christians, who is venerated in the shrine of Sheshan in Shanghai.
"To the Chinese Catholics I say: let us raise our gaze to Mary our Mother, so that she help us to discern the will of God regarding the Church's concrete path in China and sustain us in welcoming with generosity her project of love."
"May Mary encourage us to offer our personal contribution for communion among believers and for the harmony of society as a whole," he said, urging Chinese Catholics not to forget to "bear witness to the faith with prayer and with love, always remaining open to encounter and dialogue."