Fr Flannery (77), who was suspended from public ministry by the Vatican in 2012, intends to give his views on whether “religious belief as we have known it can survive in modern Ireland”.
He also intends to pay tribute to Pope Francis for “freeing up discussion, areas of study and the search for the truth”.
The Redemptorist priest had been disciplined in 2012 for publicly expressing support for women’s ordination and same-sex marriage, and for expressing more liberal views on homosexuality.
Although he has been outspoken since his suspension and was profiled in a recent TG4 documentary, he has not given a public talk with a question and answer session in six years.
He says the talk he intends to give in the Clayton Hotel, Galway on March 27 was scheduled to be given in church property several months ago.
However, when the organisers learned that the ban imposed on him applied not only to speaking in churches but to speaking in "all church-owned property", a new venue had to be found.
Fr Flannery says that in spite of his suspension, he has “studied and read” and has been contemplating “how best to address the falling attendances at Mass” and “the falling away in general from the Catholic faith”.
“If we take the traditional indications of the health of the faith as measured by the Catholic Church... then all the signs are that it is in serious trouble, and that the faith is in the terminal stage of ill health,” he says.
“Churches are emptying or are being frequented only by the older generation,” he says, noting that “seminaries are closing down, and priest numbers are declining rapidly”.
“There appear to be few, if any signs of new growth - but that is by no means the full story.
“We are living in a really interesting time in the [Catholic] church since the arrival of the papacy of Francis. Even in the 11 years since his appointment he has brought about a great deal of change,”he says.
“I have no doubt that the biggest legacy Pope Francis will leave from his time in charge is that he has freed up discussion, areas of study and the search for truth in the church - all of which had been seriously restricted for many centuries by rigid imposition of official teachings.
“The “pre-Francis” church had adopted the position that it had the full truth, and that it had nothing to learn from the world.
“Francis, on the other hand, realised that in order for the church to be relevant, it must engage with modern life, and be part of the debate about the future of the world and of people.”
He cites as examples of that attitude change “the extent to which Francis has engaged in the debate about the destruction of the environment and the necessity of facing up to climate change”.
Fr Flannery says all are welcome to his talk in Galway’s Clayton Hotel, Briarhill, on March 27, and will allow for a question and answer session.
Last year, the Association of Catholic Priests (ACP) and Lay Catholic Group (LCG) called for him to be restored to the ministry and said he had experienced a “grave injustice”.