A leading campaigner for Irish marriage equality has called on Northern Ireland politicians to support similar change north of the border.
Una Mullally said it was "absurd" that politicians continued to veto equal rights and disrespect the will of the people.
Northern Ireland is the only part of the UK and Ireland where same-sex marriage remains outlawed after the Republic voted to change the law in a 2015 referendum.
Ms Mullally said: "It is absurd that a lesbian or gay couple can get married in Dundalk but not Newry, Letterkenny but not Strabane, Clones but not Enniskillen.
"It is absurd too, that politicians continue to veto the equality and rights of people in Northern Ireland, disrespecting the will of the people, who overwhelmingly support marriage equality in the North.
"On what basis is this being done other than prejudice?"
The DUP, Prime Minister Theresa May's partners in government, has used a controversial Stormont voting mechanism to prevent a law change, despite most Assembly members supporting the move at the last vote.
The party rejects any suggestion it is homophobic, insisting it is protecting the "traditional" definition of marriage, and has called for tolerance of what are increasingly minority views.
It does not have enough members in the new Assembly to veto an equal marriage vote on its own, but there is no immediate prospect of the Stormont administration's restoration.
Ms Mullally, an Irish Times columnist who chairs the group currently overseeing the Republic of Ireland's first ever National LGBT Youth Strategy, delivers the Amnesty International Belfast Pride Lecture on Tuesday night.
She will discuss the road to equality in Ireland and said there needed to be greater solidarity between communities north and south.
"Marriage equality is not just an issue for lesbian and gay couples, it is not just about weddings, it is not just about extending access to an institution to people who have been excluded from it.
"It is about recognising that all of us are equal and deserve to be seen and treated as such.
"The politicians who oppose marriage equality need to reflect on the impetuses that are pushing them to do so.
"Prejudice, discrimination, meanness, and a lack of charity and fairness are not Christian values."
The event follows the Love Equality march in Belfast at the beginning of July when thousands of people took to the streets to call for change.
A 2016 opinion poll by Ipsos Mori indicated that 70% of people in Northern Ireland supported legislation to allow for equal marriage for same-sex couples.