(RNS) The Roman Catholic Church has sent a letter to its parishes across Scotland protesting a political race to legalize same-sex marriage.

The letter was read Sunday (Aug. 26) by priests in 500 Catholic parishes urging Scotland's political leaders to "sustain rather than subvert marriage" and to reaffirm that "marriage is a unique, lifelong union between a man and a woman."

Scotland is caught up in a debate over whether it should become the first segment of Britain to legalize gay marriage, ahead of England and Wales.

After the letter was read out in churches Sunday, the Scottish government insisted that it intends to legalize same-sex marriages and religious ceremonies for civil partnerships because "it is the right thing to do."

The issue is still in the consultation stage in England and Wales.

The letter from the Scottish Catholic leadership was part of its latest drive to keep marriage in the province on a traditional path. It called on congregations "to pray for our elected leaders ... that they may be moved to safeguard marriage as it has always been understood, for the good of Scotland and of our society."

Last week, Cardinal Keith O'Brien, who heads the Catholic Church in Scotland, described same-sex marriage as a "grotesque subversion of a universally accepted human right."

At the same time, O'Brien broke off talks over the issue with First Minister Alex Salmond, Scotland's political chief.

The Scottish government on Sunday staunchly defended its intention to make gay marriages legal. But it did add that "we are equally committed to protecting religious freedom and freedom of expression," while "ensuring that religious celebrants opposed to same-sex marriage do not have to solemnize same-sex marriage."

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