Catholic bishops in the North of Ireland will send a letter to members of the Northern Ireland Assembly to urge them to vote against a Sinn Féin motion to legalise same-sex marriage.

The Presbyterian Church has also written to politicians re-stating its opposition to any change in the legal definition of marriage, the BBC reports.

The motion is set to be debated at Stormont on Monday.

On Wednesday, Iona Institute director, David Quinn, addressed members of the Assembly at a meeting in Belfast organised by the bishops to explain why marriage should not be redefined.  

Fr Tim Bartlett, from the Catholic Council for Social Affairs, which issued the invite, told the BBC last night that marriage between a man and a woman \”still matters in society\”.

Speaking on BBC\’s The View programme on Thursday Fr Bartlett said: \”Any debate about this matter from a Christian point of view has to be framed in terms of respect, love, kindness towards each other and for each other as human beings and respect the dignity of each other.

\”Mums and dads are important and that difference between men and women in the rearing of children is important and society has always recognised that and given it a special place.\”

Meanwhile, in its letter, the Presbyterian Church has also urged MLAs to vote against Monday\’s motion.

Last year, assembly members rejected a proposal that same-sex couples should have the right to marry.

Ahead of that debate last October, the Presbyterian Church wrote to all assembly members stating its opposition to any change in the legal definition of marriage.

In its latest letter, signed by the co-convener of its Church and Society Committee, Dr Norman Hamilton, it calls for \”a much needed debate across all sections of our community on the role of the state in shaping a wide range of public and private relationships\”.

The Church claims \”renewed pressure\” for a change in the law \”suppresses and skews\” that debate.