Papal visit: Timeline of key issues for Irish Church
In 1979, half of the population of Ireland turned out to see the charismatic Pope John Paul II. The Polish pontiff received a rock star's welcome and his open-air Mass in Dublin's Phoenix Park drew 1.25 million people, the largest event in the state's history.
"Semper Fidilis" he said as he left Shannon Airport, and with 90% of the people regularly attending Mass and the Catholic Church controlling almost the entire school system, it did seem Ireland would be "always faithful".
Since then a steady stream of child sex abuse scandals have destroyed the moral authority of the Church and weekly Mass attendance in some parts of the country has fallen to 30%.
Here are some of the key dates in the relationship between the Church and the Irish state.
1937 - The Irish Constitution recognises in Article 44 "the special position of the Holy Catholic Apostolic Church as the guardian of the faith professed by the great majority of the citizens".
1972 - Voters approve a constitutional amendment repealing Article 44.
1973 - The Irish Supreme Court declares a right to marital privacy which includes contraceptive use, but declines to overturn laws prohibiting their sale.
1979 - In July the Health (Family Planning) Act becomes law, allowing pharmacists to give contraceptives to anyone with a doctor's prescription.
John Paul II visits
1979 - Pope John Paul II arrives in Ireland on 29 September for a three-day visit. More than 2.5 million people attend events in Dublin, Drogheda, Clonmacnoise, Galway, Knock, Limerick and Maynooth.
1983 - The Eighth Amendment is passed, guaranteeing the right to life of the unborn in almost every circumstance.
1986/7 - Dioceses around Ireland take insurance against claims of clerical child sex abuse.
1987 - David Norris becomes the first openly-gay person elected to public office when he enters the Seanad.
Clerical abuse uncovered
1988 - Fr Ivan Payne is convicted at Dublin Circuit Criminal Court of 14 sample charges of sexually abusing eight boys between 1968 and 1987. The abuse took place while the victims were patients in Dublin's Our Lady's Hospital for Sick Children. He also abused altar boys.
The European Court rules Ireland's continued outlawing of homosexuality contravenes the European Convention on Human Rights.
1992 - The Irish Supreme Court declares a right to abortion if a mother's life is at risk, after the then Attorney General Harry Whelehan sought to stop an unnamed 14-year-old girl who was raped by a neighbour from travelling to England for a termination, despite the fact she was suicidal. She later miscarried.
1992 - The Thirteenth Amendment to the Irish Constitution is passed by a referendum. It establishes the right to travel outside the country for an abortion.
1993 - The Criminal Law (Sexual Offences) Act decriminalises same-sex relationships in the Republic of Ireland.
1994 - In June Fr Brendan Smyth is sentenced to four years in prison for abusing children in Belfast. Four months later the Irish Government falls after a row between coalition partners Fianna Fáil and Labour over Attorney General Harry Whelehan's handling of repeated extradition requests for Fr Smyth to Northern Ireland.
Victims speak out
1995 - Andrew Madden is the first victim of clerical child sex abuse to go public. Archbishop Desmond Connell denies the Dublin archdiocese paid compensation to any victim of clerical child abuse. He later explains money used to compensate Andrew Madden was a "loan" from the archdiocese to paedophile priest Ivan Payne.
1997 - A Dublin priest is jailed for 18 months for sexually abusing a young girl during the 1970s and Brendan Smyth is jailed in Dublin for 12 years for abusing children in the Republic of Ireland.
1999 - Fr Sean Fortune commits suicide in New Ross, Co Wexford, while awaiting trial on 66 charges of sexual abuse against 29 boys. He had ministered in Wexford, Belfast and Dundalk. Allegations were made against him in all three places.
2002 - March: A BBC documentary Suing the Pope highlights the case of Fr Fortune. It follows Colm O'Gorman as he investigates how the cleric was allowed to sexually abuse him and countless other teenage boys while being moved from parish-to-parish.
April 1: Brendan Comiskey, Archbishop of Ferns, resigns over claims he failed to deal adequately with allegations about Fortune. The Irish government announces an independent inquiry.
October: RTÉ's Prime Time broadcasts Cardinal Secrets on the handling by a number of bishops of clerical child sex abuse allegations in the archdiocese of Dublin. It claims the archdiocese is facing 450 legal actions as a result of abuse allegations and that at least six bishops knew about these cases.
November: The Irish government pledges to establish a full independent judicial inquiry into Dublin archdiocese's handling of abuse allegations.
The scandal grows
2004 - Cardinal Desmond Connell steps down as Archbishop of Dublin over his handling of child sex abuse in the Catholic Church.
2005 - October: The Ferns Inquiry into child abuse in the County Wexford Diocese of Ferns identifies more than 100 allegations of child sexual abuse between 1962 and 2002, against 21 priests. It concludes that Bishop Herlihy and Bishop Comiskey "placed the interests of individual priests ahead of those of the community in which they served".
November: Judge Yvonne Murphy is appointed to head a Commission of Investigation into the Dublin archdiocese.
2009 - January: The Dublin Commission of Investigation remit is extended to include the archdiocese of Cloyne, which covers most of mid, east and north Cork.
May: Ryan Report details widespread abuse of children in Ireland's residential institutions run by 18 religious congregations. It took submissions from 2,000 people who said they had suffered physical and sexual abuse while in the care of Catholic-run institutions.
November: The Murphy Report says police colluded with the Catholic Church in covering up decades of clerical sex abuse in the Dublin archdiocese. Justice Minister Dermot Ahern says: "The persons who committed these dreadful crimes will continue to be pursued. Justice - even where it may have been delayed - will not be denied." A number of bishops offer their resignations to the Pope following the report's publication.
Gay rights on the march
2010 - The Civil Partnership and Certain Rights and Obligations of Cohabitants Act allows for civil unions between same-sex couples.
2011 - July: The Cloyne Report reveals Bishop John Magee - who stood down in March 2009 after serving as bishop of Cloyne since 1987 - falsely told the government and the health service that his diocese was reporting all abuse allegations to authorities. It also exposes an attempt by the Holy See to frustrate the inquiry. Taoiseach Enda Kenny launches an unprecedented criticism of the Catholic church, saying: "The rape and torture of children were downplayed or 'managed' to uphold instead the primacy of the institution, its power, standing and 'reputation'."
November: Cardinal Sean Brady expresses his "profound disappointment" after the Irish government closes its embassy to Vatican City over the Holy See's handing of clerical child sex abuse scandals in Ireland.
2012 - May: The BBC This World programme discovers that in 1975 the Catholic Primate of All-Ireland Sean Brady had the names and addresses of those being abused by paedophile priest Brendan Smyth, but did not ensure their safety.
October: Savita Halappanavar dies in University Hospital Galway. The 31-year-old dentist was 17-weeks pregnant and miscarrying when staff refused a request for a termination. She died as a result of septic shock from an E-coli infection.
2013 -The Protection of Life During Pregnancy Act is passed, allowing for abortion if a woman is suicidal.
2014 - Pope Francis asks for forgiveness for the "evil" damage to children caused by sexual abusers in the clergy. He says the abuse was a "moral damage carried out by men of the Church", and that "sanctions" will be imposed.
2015 - May: The same-sex marriage referendum, the thirty-fourth amendment to the Irish Constitution, is passed with 62% of those who voted supporting the change.
Abortion laws swept away
2015 - The first openly-gay cabinet minister, Leo Varadkar, the son of an Indian immigrant, becomes health minister.
2015 - The Gender Recognition Act becomes law, allowing people to define their own gender.
2016 - Katherine Zappone becomes Ireland's first openly-lesbian cabinet minister when she is appointed Minister for Children and Youth.
2017 - Leo Varadkar becomes Taoiseach.
2018 - February: The Department of Education orders Catholic schools to change religion classes from an opt-out to an opt-in requirement.
May: A referendum on the Eighth Amendment to the Irish Constitution votes by 66.4% for its repeal, clearing the way for legalised abortions in Ireland.