A landmark vote to allow same-sex marriage in the Republic of Ireland was a "defeat for humanity", a senior Vatican official has said.
Cardinal Pietro Parolin, the Vatican's secretary of state, said he was "very saddened" by the result.
In the referendum, 62% were in favour of changing the Irish constitution to allow gay and lesbian couples to marry.
However, Cardinal Parolin said it showed the church needed to improve how it preached the Christian message.
The senior diplomat made the comments during a conference in Italy on Tuesday night, according to the Italian news agency, Ansa.
"The Church must take account of this reality, but in the sense of reinforcing its commitment to evangelization," he said.
"I think that you cannot just talk of a defeat for Christian principles, but of a defeat for humanity.
"The family remains at the centre and we have to do everything to defend it and promote it.
"Hitting it would be like taking the foundations away from the building of the future".
Soon after taking office, Pope Francis commented: "If a person is gay and seeks God and has good will, who am I to judge him?"
Diarmuid Martin, Archbishop of Dublin, said the Church in Ireland needed to "reconnect" with young people.
In Italy, the government of Prime Minister Matteo Renzi is preparing to present legislation that would allow civil unions between gay couples.
The Irish referendum has also boosted calls in Germany, which allow same-sex civil unions, to go further and legalise same-sex marriage.
Pressure has started to grow in Chancellor Angela Merkel's Christian Democratic Union (CDU), which opposes any change.
"One would think that what the Catholic Irish can do, we can do too," CDU parliamentarian Jens Spahn told the German Die Welt newspaper.
The yes result has also led to calls for the introduction of same-sex marriage in Northern Ireland.
The first gay marriages are likely to take place in the Republic of Ireland in early autumn.
Same-sex marriage is now legal in 20 countries worldwide.