Outspoken US cardinal Raymond Burke has blasted Yes voters in Ireland's same-sex marriage referendum saying they are worse than pagans and defying God.

Burke, a key Vatican figure under Pope Benedict, was demoted under Pope Francis for his hard-line views. However he still is considered a very powerful figure in the US church. He was Archbishop of St. Louis from 2003 to 2008.

“I mean, this is a defiance of God. It’s just incredible," Burke told Oxford University's Catholic Society this week. "Pagans may have tolerated homosexual behaviors, they never dared to say this was marriage.”

Burke's perspective on the historic Irish vote contrasted sharply with the Archbishop of Dublin, Diarmuid Martin's, who told RTE this week that “the Church needs a reality check right across the board - and to ask have we drifted away completely from young people?”

But Burke, an arch conservative noted for his love of ornate clerical garb, has no interest in altering his own hardline approach in order to appeal to the young or to address their concerns. 

“The life of the Church is organic," he told the Catholic Society. "It is a living tradition handed down in an unbroken line from the apostles. It does not admit of discontinuity, of revolutions.”

The Irish cast 1.2 million Yes votes in favor of same sex marriage with 734,300 voting No, making Ireland the first country in the world to introduce gay marriage by popular vote.

Burke and other conservative church members believe that a course correction to attract younger people is neither worthwhile or possible. Instead they suggest more aggressive evangelization is the solution. 

But critics say doing the same thing, only more aggressively, will serve to further erode the church's standing, not enhance it. 

Meanwhile a prominent American canon lawyer has branded all Yes voters in the recent marriage referendum potential "heretics."

Dr. Edward Peters, who was appointed a Referendary of the Apostolic Signatura by Pope Benedict in 2010, has described the outcome of the constitutional referendum on marriage in Ireland as "a disaster."

"Any Catholic who directly helped to bring about Ireland’s decision to treat as marriage unions of two persons of the same sex has, at a minimum, arrayed himself against the infallible doctrine of the Church and, quite possibly, has committed an act of heresy," Dr Peters wrote on his Canon Law Blog this week.

The technical term for voting to allow same sex marriage is “sin”, wrote Dr. Peters, "and the consequences of sin are always spiritual and sometimes canonical; and the solution for sin is repentance and Confession."

Dr. Peter's counsels his readers not to pursue potential excommunications for the political leaders who led the nation toward the referendum, instead he suggests they focus their efforts on "righting" the result "as soon as possible."