A Jesuit priest said a Vatican invitation for him to speak on pastoral care for the families of gay and lesbian people is "a huge moment" for the Catholic Church.
US priest Fr James Martin will travel to Dublin to address the World Meeting of Families (WMOF) on how parishes worldwide should 'build a bridge' of welcome for gay and lesbian parishioners.
He believes Pope Francis "is bound to shake things up" generally when he arrives in Dublin in August for the global event.
Pope Francis has not changed Church teaching on homosexuality but the Pope changed the Church's tone towards gay people which resulted in many members of the LGBT (Lesbian, Gay, Bi-Sexual and Transgender) community returning to Church life in the US, he said.
Fr Martin has been criticised by traditionalists for his views. He was appointed by the Pope to the Vatican's Secretariat for Communications last year.
The Pope will speak on a number of occasions over two days when he arrives in Ireland on Saturday, August 25, for the Church-organised WMOF events.
Pope Francis will speak at a State reception at Dublin Castle shortly after noon following his visit to the president at Aras an Uachtarain.
Pope Francis will speak at St Mary's Pro-Cathedral in Dublin at 3.30pm and then spend private time with homeless families at the Capuchin Day Centre in Dublin.
That evening, he will make a speech at the Festival of Families concert in Croke Park.
On Sunday, the Pope will pray the Angelus at Knock Shrine in Co Mayo shortly after 10am.
He will fly back to Dublin to celebrate a Mass at 3pm for a huge public gathering in the Phoenix Park before returning to Rome.
He is expected to meet some victims of clerical sex abuse during his Irish visit.
New York-based Fr Martin (57) told the Sunday Independent he expects the Pope to make a big impact in Ireland.
"I would say get ready to be surprised because Pope Francis usually upends people's expectations of what he is going to do or say on his trips.
"When he came to the United States, he really dazzled people by not only his words but his deeds. It was really extraordinary. People fell in love with him.
"He is an authentic apostle. And holiness is naturally attractive. He is bound to shake things up, one way or another," said Fr Martin.
The Pope's approach to LGBT people is markedly different from past pontiffs, said the priest.
"He has an entirely different flavour to his message than previous popes. His five most famous words are 'Who am I to judge?'
"That was initially about gay priests but it was expanded to include LGBT people. He has used the word 'gay' repeatedly. He has gay friends. He said that Jesus would never say to a gay person 'go away from me'.
"And the way he reaches out to LGBT people - they feel more comfortable going to church, they simply do," he said.
Controversy erupted in Ireland a few months ago when Church traditionalists succeeded in forcing the removal of images of a same-sex couple from a preparation booklet for the Dublin WMOF event.
That showed the Church was "still struggling" with the issue, he said.
"But then the invitation from the Vatican for me to speak about LGBT issues in a positive way is a huge moment in the church.
"It's not about me, it is what it says to LGBT Catholics. This would never have happened five years ago.
"In the end, the invitation for someone to talk positively about LGBT families shows what they really think," he said. Fr Martin has reportedly highlighted the need for the Church to address its use of language in the past which referred to LGBT people as "intrinsically disordered".
The use of such terminology is the focus of a petition by Irish Catholic reform group We Are Church Ireland.
The group is to petition the Pope to address the use of such homophobic terms.
Fr Martin went on to say: "Archbishop Martin said during the press conference that the World Meeting of Families is for all families and all Catholics and that includes families that have LGBT members and even LGBT families," he said.
Fr Martin welcomed the endorsement of three cardinals for his new book, entitled Building a Bridge.
He said it would be important that Pope Francis, even with his limited time in Ireland, that he addresses the question of clerical sex abuse.
"The Church can never do enough for the victims of sex abuse. Any time Pope Francis has been meeting with victims or confronting those issues, is time well spent," he said.
"It's not a crisis that is over.
"We need to continue to listen, apologise, and accompany these victims and make sure sex abuse never happens again," he said.
"I would say don't underestimate the change that has happened with regard to LGBT people over the past five years. Five years ago my book would not even have been published. That's a big change," he said.
Fr Martin was a former executive in the US financial sector who later joined the priesthood.
He said his own address at the WMOF event in Dublin will be about how parishes can be more welcoming to LGBT Catholics, their parents, their grandparents, their brothers and sisters.
His basic message to parishes on how to reach out to LGBT people will be: "Listen to them, listen to them, listen to them.
"My experience in the United States varies dramatically. In general, parishes in larger cities with greater concentrations of LGBT Catholics are doing a much better job with LGBT outreach groups, LGBT retreats, and LGBT support groups for parents.
"But then you might get a parish in a very small town that has a homophobic pastor and they are doing nothing. Or worse, they are discouraging, or insulting or excluding LGBTs either explicitly or implicitly. Some of the stories are just appalling.
"A 30-year-old autistic man came out to his family. One of the pastoral associates of the parish told him that, even though he was not in a sexual relationship, he could no longer receive Communion because he was gay and it was a scandal and that, maybe, if he wanted to, he could stop by the rectory once in a while to receive Communion.
"In the good parishes, with retreats for LGBT people, they have parish announcements about parish LGBT groups holding retreats.
"Those parishes have an open invitation to LGBT people. In other words, it is almost indistinguishable from other ministries," he said.
In general, he said the message is clear: "Just love them."