Legal expert Alan Sears said that the push for marriage redefinition in the U.S. has provided a platform for the issue at large and that Pope Francis' visit in 2015 could mark a shift in the contentious debate.

"This could be a turning point in the struggle for marriage," he told CNA Nov. 26. "The Holy Father has the opportunity to speak in the USA, to step into the middle of this with the message of love, with a message of hope to clarify and help people to understand the beauty of God's design."

Sears serves as president of the international legal group Alliance Defending Freedom, which specializes in the protection of religious liberty worldwide. He was recently in Rome for the Nov. 17-19 colloquium on the complementarity of man and woman in marriage that was attended by Pope Francis.

Also referred to as the "Humanum" conference, the gathering was sponsored by the Congregation for the Doctrine of the Faith, in collaboration with the Pontifical Council for the Family, the Pontifical Council for Interreligious Dialogue, and the Pontifical Council for the Promotion of Christian Unity.

The meeting came amid the ongoing push for the legalization of same-sex "marriage" in the U.S. – a contentious issue that's has left many Catholics divided. Sears believes many people today are deeply confused about the true nature of marriage and unaware of the security it provides to both individual families and society at large.

Pope Francis' to Philadelphia for next year's World Meeting of Families could likely be just as impactful as that of St. John Paul II on the pro-life movement when he came to Denver, Colo. in 1993 for World Youth Day, he said.

"One of the most incredible speeches was that which (John Paul) gave on the culture of life," Sears recalled. It "was a turning-point moment" for the many in the pro-life movement whose work had largely been "pushed to the way-side" by secular press and those advocating abortion. Through his speech St. John Paul II sparked a new dimension of pro-life work that was founded on God's plan for humanity and the joy that life brings, he reflected.

And what we are seeing now is an "incredible turn of public opinion," so much so that "the pro-life movement is not too far away from a tipping point for victory."

In this context, the visit of Pope Francis – at a time when the debate on marriage is so fierce – could be the opportunity those fighting for traditional marriage have been waiting for, Sears observed.

He explained that right now many U.S. courts "have chosen to redefine marriage through extra constitutional means, and assert that things which were always considered to be consistent with the constitution are unconstitutional, and many people just don't understand this."

He said that placing emphasis on the beauty of marriage during the papal trip could be a key step in helping society to understand the enormous benefits, love and protection growing up in a family with both a mother and a father provides to children.

"People try to cover and say the only reason this is so bad with this attempted redefining and claiming something else as marriage is because of society's discrimination. That's not so," Sears said.

"The ideal best – every study, experience shows and culture has shown for thousands of years – is a mother and a father committed to each other for life."

Sears recalled a video that was shown during the marriage colloquium in which a man currently involved in a homosexual relationship in France gave his testimony about wanting to adopt children with his partner.

After initially talking about their mutual desire to have children, the couple began to research about parenting and raising children.

They eventually the couple decided that they shouldn't have children since "it would be an act of selfishness for us because we recognize we would be creating a situation of permanent motherless-ness that would be unnecessary for children."

Sears said Pope Francis has an opportunity during his visit to suggest concrete efforts people can make to both uphold and celebrate marriage, such as renewing wedding vows.

The beauty of marriage "is one of the great confusions because people don't understand the joy marriage between a man and a woman brings that all other substitutes do not provide," he said

Sears noted how throughout his world travels, one thing he has constantly encountered in each place in the thousands of people he meets is a lack of knowledge and formation on Church teaching and scripture as it relates to marriage.

So even "a simple sermon going back to the basics (of marriage), like John Paul's simple sermon going back to the basics of life" would be greatly effective coming from the Pope, he said.

Alan Holdren contributed to this report.