The Very Rev Kelvin Holdsworth of the Scottish Episcopal Church is to hold a special open service at his church, St Mary's Cathedral in Glasgow, tomorrow in direct opposition to the Catholic Church's National Marriage Day.
The Catholic Church, which has been hugely critical of plans by the Scottish Government to legalise same-sex marriage, has reacted with fury.
But Mr Holdsworth defended the service, saying it is being held for anyone who wants to be able to worship in a church "where gay people are welcomed and not marginalised".
Mr Holdsworth said he, and some of his colleagues, have been approached by members of Catholic congregations who are upset at being told what to think by senior bishops and members of the clergy.
He said: "Over the summer, I've been contacted a number of times by people who have asked me whether they can come to St Mary's Cathedral on a one-off basis on Sunday.
"The people who have contacted me about this upcoming Sunday to ask if they can join us for a week are quite varied.
"Some are straight people and some are gay.
"Some are Roman Catholics who simply don't want to be told what to think about this topic and who reject the current rhetoric coming from the Scottish Roman Catholic Church."
The open invitation to worship at the cathedral on Great Western Road at 10.30am was issued on Mr Holdsworth's online blog, where he brands the Catholic Church's stance on same-sex marriage "hugely negative".
He said: "I believe in equal marriage and hope it comes soon. The trouble is, the rhetoric that is currently coming from the Roman Catholic Church on this topic can be hugely negative. We saw that on STV's Scotland Tonight on Thursday evening when one of their spokesmen once again asserted that gay people live shorter lives than straight people and seemed to suggest that people needed to be 'warned' against being gay.
"I don't think that it is unreasonable to describe it as homophobic and that is a word I almost never use. It is also my view that the attitude of the Scottish Roman Catholic Church's hierarchy seems to be at odds with the membership of that Church whom I generally encounter as gentle, respectful, and kind."
The service has been welcomed by the Equality Network, which works to promote rights for works for lesbian, gay, bisexual and transgender people
Spokesman Tom French said: "We have no problem with the Catholic Church doing what they want, and it has to be stressed that no religious body is going to be compelled to perform same-sex marriages.
"But it's really great to see the Episcopal Church is showing not all religious groups oppose same-sex marriage."
The Catholic Church declined to comment on the Episcopal Church's invitation to its congregation. But one senior source said: "This is an unprecedented attack on another Christian Church, using language which is incendiary and uncharitable, and it is probably best left for the hierarchy of the Episcopal Church to deal with."
A Scottish Government spokeswoman said: "We intend to proceed with plans to allow same-sex marriage and religious ceremonies for civil partnerships.
"However, we are equally committed to protecting religious freedom and freedom of expression, and ensuring religious celebrants opposed to same-sex marriage do not have to solemnise same-sex ceremonies."
A spokeswoman for the Episcopal Church said Mr Holds-worth's views were his own, and that he was not speaking for the Church as whole.