He received his primary education in Kiltealy National School, and his secondary education in St Peter’s College, Wexford. He then entered the seminary wing of the same college and was ordained there on 31 May 1970. In September that year he became a member of the Missionaries of the Blessed Sacrament at the House of Missions, Enniscorthy, and conducted missions and retreats in Ireland, Britain and Newfoundland. He was the last Superior of the House of Missions before its closure in 1992 and then was assigned as Administrator of St Senan's Parish, Templeshannon, from December 1986, and was appointed parish priest of Taghmon in March 1997. He served as Vicar Forane for the Wexford deanery and as the diocesan delegate charged with child protection, and was a member of the diocesan Council of Priests.
Child protection and payouts
Brennan is regarded by many as bringing a stability to his diocese after the disclosures of 100 episodes of child sexual abuse as described in The Ferns Report which occurred during the tenure of his predecessors, Bishop Donal Herlihy and Brendan Comiskey. In March 2010, Bishop Brennan told parishioners that the diocese had had to pay more than €8 million to settle 48 civil actions, while a further 13 actions were pending. Brennan said a request for financial help from parishioners was not about sharing blame, but about "asking for help to fulfil a God-given responsibility". He said people who suffered abuse were not the cause of the diocese's problems. Instead, the actions of "individual perpetrators, along with mismanagement, poor understanding and/or lack of resolve" were to blame. "The Diocese of Ferns has been on a road involving the settlement of claims for 15 years now. It has been very much a team effort – various administrations and personnel, local diocesan and national church funding," Dr Brennan said. "Up to 80 per cent of the road of justice has been travelled. As we look to complete this road, it will be necessary to invite the parishes to become part of the process financially.". The diocese estimated it would need to raise €60,000 a year from its 100,000 parishioners over a period of 20 years. An alternative plan was to sell assets and properties, including the Bishop's House in Wexford, St Peter's College Seminary, or agricultural land. Diocesan officials insisted none of the money from weekly collections would go towards settlement costs. The diocese paid the balance through savings, remortgaging the bishop's residence, and raising a €1.8 million loan. It paid out a further €2.1 million on legal fees for abuse inquiries, and €836,000 towards the treatment of paedophile priests.
2010 Vatican summit
Bishop Brennan took part in the summit with Pope Benedict XVI and senior curial heads on 15–16 February 2010 to discuss the Ryan report and Murphy Report that were published in 2009. Brennan said that the Irish bishops' meeting with the pope was a "watershed moment" that would redefine the relationship between the Church and abuse victims, adding that a number of points regarding the mishandling of abuse cases by Church authorities were made by bishops "very honestly" in the presence of the pope. "The Holy Father has heard the many stories of Irish victims and I can also say they have been believed,” he told RTÉ's Morning Ireland programme today. "To have the Holy Father there for a day and a half, and the nine heads of the Vatican congregations shows how seriously the Church is taking the issue."Asked why certain issues such as the high-profile resignations of bishops and the findings of the Murphy report were not addressed, Bishop Brennan said the meeting was primarily a briefing session for the pope to help him formulate his forthcoming pastoral letter to Irish Catholics. The day after the unprecedented summit Brennan said that the issue of resignations was not on the agenda at talks between the Irish bishops and Vatican officials. He was responding to criticism from victims' groups who expressed disappointment at the failure of the talks to address several issues relating to the church's handling of child abuse cases.
