Archbishop of Dublin Diarmuid Martin has said he fears that same-sex couples who are turned away from a church for their marriage could take legal action.
Dr Martin conceded that the 'Yes' vote victory in the marriage equality referendum is a sign of a cultural revolution.
He also said the result shows there is a substantial divide between Irish society and the Catholic Church.
In an interview with the Vatican Insider, the archbishop said he knew the game was up for the 'No' campaign when he saw people queuing outside polling stations before the doors opened.
He said that the change to the definition of marriage will have "unforeseeable concrete consequences".
"The Catholic Taoiseach has given his assurance that churches will not be affected, the courts will be responsible for implementing the law," he said.
"Religious marriage is also a civil marriage and same-sex couples who are turned away by their parish priest could turn to judges, accusing us of discrimination if lawmakers do not set certain limits.
"In Catholic schools, civic education teachers will be obliged to say that marriage is also the union between people of the same sex. All of this will create problems."
Faced with criticism from conservative Catholics that he had not done enough for the 'No' cause, Dr Martin said that even proponents of the referendum were shocked at the scale of the 'Yes' vote.
"Health Minister Leo Varadkar said it was not a referendum but a cultural revolution. The Church needs to ask itself when this cultural revolution began and why some members refused to see this change," he said. "The vote reflects the current situation in Irish culture.
Meanwhile, Senator David Norris, speaking on the Pat Kenny Show on Newstalk, said the downside of the 'Yes' vote was that there would be a glut of "ghastly weddings".
"I don't like weddings," he joked.