The former leader of the Alliance Party Lord John Alderdice has resigned from the Presbyterian Church following a decision not to allow those in same-sex relationships to be full members of the Church.
He sent a letter of resignation to the Presbyterian Church centrally and to his local Church.
The former Stormont Speaker outlined three main reasons for his decision.
He said he had been unhappy with the decision to leave the World Council of Churches and the decision to loosen ties with the Church of Scotland.
He also cited the ruling from the Church's General Assembly that people in same-sex relationships could not be full members.
Lord Alderdice, who is planning to relocate to England from Northern Ireland, is the son of a Presbyterian Minister and has been involved with the Church throughout his life.
"This has been a very difficult personal decision," he told BBC Northern Ireland's The View programme.
"It's no longer possible to defend the position of the Presbyterian Church or for me to feel that it's an appropriate expression of my faith so I've decided that after 30 years as an Elder and a lifetime as a member to resign from the Eldership.
"That's a very difficult and painful decision, but is one that has come about over a period of time watching the direction of things."
Rev. Trevor Gribben, Clerk of the General Assembly and General Secretary of the Presbyterian Church in Ireland paid tribute to Lord Alderdice following his resignation.
“Any resignation from the Church is to be regretted. Lord Alderdice has had a distinguished career in variety of fields helping many people as a consultant psychiatrist and in leadership stepping into politics at a difficult time to lead the Alliance Party," Rev. Gribben said.
"He has continued that public service in different arenas as Assembly Speaker, a member of the International Monitoring Commission and now as a member of the House of Lords. Not least, of course, is his commitment to his local congregation and as an elder in Knock Presbyterian where he has served the Lord for 30 years.
"He has a right to his own opinion, even when they differ from the clearly agreed position of the Presbyterian Church in Ireland through our General Assembly. I would also like to take the opportunity to wish him well as he moves to England and trust that he will quickly find a new Church family close to his new home.”
Former Moderator of the Presbyterian Church in Ireland the Very Rev Dr Stafford Carson, convener of the church's Doctrine Committee, insisted that the Church would not be changing its mind on same-sex relationships.
"We should set aside our own choices and preferences willingly, to live in a way that pleases Him who loves us beyond measure," he said.
"We are called to honour and love Christ, even if this means we come into conflict with society's prevailing views on this and other issues."