Pope Francis issued a letter to the Knights of Columbus on the occasion of their 131st annual convention, praising them for their charitable works and encouraging them to defend the faith.

Sent by Vatican Secretary of State Tarcisio Cardinal Bertone on behalf of Pope Francis, the letter expressed the Pope's "esteem for the ideals of faith and fraternity" that the Knights embody, as well as their "commitment to the Church's mission, and the many works of charity and evangelical witness" they have undertaken.

The letter was directed to the more than 2,000 Knights and their families who attended the San Antonio conference for the purpose of prayer, planning, recognition and fellowship. Present at the August 5-8 conference this year were Knights from dozens of countries, as well as more than 100 members of the Catholic hierarchy, including numerous bishops and 11 cardinals.

Pope Francis reminded the Knights of the importance and responsibility of the lay faithful in the Church, and encouraged every Knight and council to continue "to bear witness to the authentic nature of marriage and the family, the sanctity and inviolable dignity of human life, and the beauty and truth of human sexuality."

"In this time of rapid social and cultural changes, the protection of God's gifts cannot fail to include the affirmation and defense of the great patrimony of moral truths taught by the Gospel and confirmed by right reason, which serve as the bedrock of a just and well-ordered society."

The Pope also conveyed his appreciation for the Knights' "clear public witness" in the forum of religious freedom, and for "protecting the right and duty of believers to participate responsibly, on the basis of their deepest convictions, in the life of society."

The Knights of Columbus was founded in 1882 by Father Michael McGivney, a parish priest in New Haven, Conn.

With charity as its central commitment, the organization has grown to 1.8 million members worldwide. During the past year, Knights donated more than $167.5 million and more than 70 million hours of service to charitable causes.

The theme for this year's conference, "Be Protectors of God's Gifts," was drawn from Pope Francis' inaugural homily in March.