Next year's synod, which will focus on young people, must address their most pressing problems, including indifference and disillusionment, U.S. bishops said at their annual meeting on Wednesday.

"The synod indeed comes at a critical time," Cardinal Joseph Tobin of Newark told fellow U.S. bishops of the upcoming Synod on Young People, the Faith, and Vocational Discernment, to be held in 2018 at the Vatican.

Cardinal Tobin cited today's pressing concerns, like the "rise of the Nones" – or young people with no religious affiliation. An "increased amount of disconnected Millennials is certainly a concern for us, as is the decline and delay of marriage among young people," he added.

The U.S. bishops discussed the upcoming synod at their annual spring general assembly, held this year in Indianapolis from June 14-16.

Among the agenda items for the morning of June 14 was an address from Archbishop Christophe Pierre, Apostolic Nuncio to the United States, to the bishops, where he called for "missionary discipleship" in the Church to "go to the peripheries" of society.

Afterward, Cardinal Tobin, along with Archbishop Charles Chaput of Philadelphia, led a discussion about the upcoming synod, an international gathering of bishops which will focus on "young people, the faith, and vocational discernment."

"Through every phase of this Synod, the Church wants again to state her desire to encounter, accompany and care for every young person, without exception," a preparatory document for the 2018 synod released in January stated.

"The Church cannot, nor does she wish to, abandon them to the isolation and exclusion to which the world exposes them," the document added.

Both Archbishop Chaput and Cardinal Tobin exhorted their brother bishops to promote a survey of youth available online at youth.synod2018.va. It is intended for those between the ages of 16 and 29, both active Catholics and "indifferent" Catholics. The feedback of those working with youth – like youth ministers – is also vital, they insisted.

"This is a time to learn from youth and young adults," Cardinal Tobin said. "They must have as much at stake in this as we do."

According to a 2015 Pew Research report, 35 percent of those in the Millennial generation (born 1981-1996) were religious "Nones."

However, there are also positive trends among young people, which include a high interest in the liturgical seasons of Advent and Lent, he added, and positive results of parish outreach ministries.

Other bishops weighed in on issues pertinent to young people.

Bishop Felipe Estevez of St. Augustine, Fla. said that the youth have been drawn to Eucharistic Adoration and have a "renewed appreciation for silence and desire for silence which manifests a thirst for spiritual life, for growth in the knowledge of the Lord."

"We need to develop more the theology of gift," he added, in a culture of "pragmatism" and "functionality."  Meditation on the gift in the Cross "needs to be internalized in the discernment of a vocation," he said.

Many young people are struggling with racism prevalent in society and are "angry and disconnected from the political process," Bishop Jaime Soto of Sacramento added.

(Story continues below)

The Church should think of "how to engage" these disaffected youth, who "feel in many cases disowned by the more traditional institutions and organizations that were important to their parents and grandparents," he said.

Invitation needs to be a theme of evangelization at the synod, said Archbishop Timothy Broglio of the Archdiocese for Military Services, USA. He insisted that active Catholics need to invite their peers to prayer and to the Mass.

Bishop Robert Barron, auxiliary bishop of Los Angeles and founder of Word on Fire ministry, pointed to intellectual objections or challenges to the faith among many young baptized Catholics, like struggles with believing in God and perceived conflicts between religion and science.

The language of missionary discipleship and the sacraments is "opaque" to them, he said, insisting that "we have to clear the ground in a significant way" through a "new apologetics."

The bishops must "think through this issue of addressing some of these real intellectual difficulties young people have before we can plant the seed of effective evangelization," he said.

Dr. John Cavadini, a theology professor at the University of Notre Dame, started the discussion by addressing the bishops on the centrality of the sacrament of Baptism to vocational discernment.

In addition to being a theology professor at Notre Dame, Cavadini is also the director of the McGrath Institute for Church Life at the university, and previously served on the International Theological Commission from 2009, when he was appointed by Pope Benedict XVI, until 2014.

"We hear lots of exhortations for young people to change the world," he noted, but "this can actually verge on secularizing the baptismal vocation" in making it "a vocation of the world."

Rather, he said, discussion must emphasize the "mystery of the Church."

"Meditating on the mystery of the Church" is not thinking about it as a charter or a constitution of some club, he insisted. Rather, it is about meditating on the "wounds of Christ from which His most previous blood flowed" which is the real birth of the Church.

"Meditating on one's dwelling near, and even in, the wounds of Christ," he said, brings about an "intimacy of love," to which "one's only response can be 'Thank you, Lord, for this love'."

Catholics should also see Christ's example of "self-emptying love" which is reflected in the Church, Cavadini said.

"The one who loves the Church loves the love who had no contempt for anything human, but did not spare Himself," he said, noting that Jesus reached out to sinners.

"He didn't back away from that solidarity" even when the penalty for it was death, Cavadini said. Rather, He "received the blow, and so transfigured the whole of human solidarity" from "solidarity in sin" to solidarity "in His love."

"The Church is the sacrament of that solidarity in the world," he added, "a solidarity which the world cannot give itself, which does not come from the world" but is "for the world."