Pope Francis has called on Roman Catholics to support the family and defend marriage.

He was speaking to a 7,500-strong gathering of the Schoenstatt Apostolic Movement, set up a century ago as an agent for spiritual renewal.

His comments came in the wake of the Synod on the Family earlier this month, which reasserted traditional Catholic teaching on divorce and homosexuality while urging a more sensitive and welcoming pastoral approach.

Responding to wide-ranging questions from the audience, he criticised the downgrading of the Catholic understanding of the family, saying that it was more than just another form of "association".

"At present, from a sociological point of view and from the point of view of human values, as well as, in fact, of the Catholic Sacrament, of the Christian Sacrament, there is a crisis of the family, a crisis because it is hit from all sides and left very wounded," he said.

He added that the sacrament of marriage was "devalued", claiming that the Church was witnessing its reduction to a "social event".

However, in keeping with the emphasis on pastoral realities that has marked his papacy, Pope Francis called on the Church to "waste time" in supporting marriage, following the example of Christ. "The great teacher of wasting time is Jesus," he said. "He wasted time to support, to have consciences mature, to heal wounds, to teach. To support is to journey together."

He urged that engaged couples should be prepared for marriage and learn to understand the meaning of "forever" which runs against today's "culture of the provisional". He warned of the dangers of new types of cohabiting relationships, saying: "They are new forms, totally destructive and limiting of the grandeur of the love of matrimony."

The Pope called for person-to-person help for married people, "supporting and not engaging in proselytism, because this does not lead to any result: to support with patience".

In other comments to the gathering, Pope Francis urged the importance of a consistent Christian testimony, saying: "Witness! To live in such a way that others are conquered by the desire to live as we do. Witness, there is nothing else. To live in such a way that others are interested and ask: 'Why?' It is witness, the path of testimony – there is nothing that surpasses it. Witness in everything. We are not anyone's saviour; we are transmitters of him who saved us all."

He added: "A closed Church, movement or community gets sick. A movement, a Church, a community that goes out, makes mistakes ... It makes mistakes, but how lovely it is to ask for forgiveness when one is mistaken! Do not be afraid to go out on mission, to go out on the road! We are walkers."

Echoing his frequent emphasis on the need for the Church to leave its areas of security to work along the poor and marginalised, the Pope said that prayer helped him to see truth "from the periphery". "When one is shut-in in a small world – the world of a movement, of the parish, of the archbishopric, or here, the world of the Curia, then one does not cling to truth. Yes, perhaps one clings to it in theory, but one does not cling to the reality of truth in Jesus. The truth is grasped better from the periphery rather than from the center. This helps me."

He spoke of calls to renew Church institutions like the Curia, the Vatican's administrative organisation, and the Vatican bank. "All of these are external renewals: this is what they say daily ... It is curious, no one speaks of renewal of the heart. They do not understand at all what is meant by renewal of the heart, which is sanctity, renewing everyone's heart."