"We must walk together: the people, the bishops and the pope," said Cardinal Lorenzo Baldisseri, introducing the synod's work Oct. 6.

Standing next to Pope Francis and quoting Pope Francis, the cardinal told the roughly 250 synod participants they were called "to work always to overcome every conflict which wounds the body of the church. United in our differences -- there is no other Catholic way to be united. This is the Catholic spirit, the Christian spirit: to be united in our differences."

Cardinal Baldisseri said the synod preparation, including the worldwide consultation and response to a questionnaire sent out on the theme of family life, already was a sign of "fraternal communion."

"This broad freedom of expression must also characterize this synod assembly because expressing one's convictions is always positive as long as it is done in a respectful, loving and constructive manner," he said.

Just as the responses to the questionnaire demonstrated a wide variety of approaches to some of the most contested and controversial areas of Catholic teaching on the family -- including contraception, divorce and remarriage, same-sex marriage, premarital sex and in vitro fertilization -- so did public discussion of the theme by several cardinals and theologians.

Opening the synod's first working session, Cardinal Baldisseri said, "Broad freedom of expression must also characterize this synodal assembly because expressing one's convictions is always positive as long as it is done in a respectful, loving and constructive manner."

The cardinal concluded his introduction praying that the Oct. 5-19 assembly would be an expression of collegiality, "which proclaims the Gospel by walking, and that it might be imbued with a new openness to the Spirit, by an approach and manner of life and witness which ensures a unity in diversity and apostolicity in catholicity."