Lesbian activist Monica Hingston has challenged her cousin, Catholic Cardinal George Pell, to a public debate on the church's attitude towards homosexuality.
Cardinal Pell is well known for his public sermons against homosexuality and sparked controversy when, as Archbishop of Melbourne, he refused gay activists holy communion.
In January, he refused to respond to a publicised letter from Ms Hingston calling on him to condone same-sex relationships, an action the Vatican has ruled out.
In her latest invitation, Ms Hingston, a former Catholic nun, urged her second cousin to debate the issue with gay Catholics at the closing of gay film festival QueerDOC.
"I encourage my cousin George to attend this event and join in the vital debate that the Catholic Church can no longer afford to ignore," Ms Hingston, 64, said.
The forum will follow a screening of In Good Conscience, a film about lesbian Sister Jeannine Gramick who was stripped of her ministry by Pope John Paul II in 2000.
"Cardinal George Pell was a member of the congregation for the Doctrine of Faith, the body that attempted to silence Sister Gramick," Ms Hingston said.
Ms Hingston, who has lived with her partner Peg Moran for 19 years, said she would be "delighted but surprised" if Cardinal Pell took up her offer.
"I'm always hopeful that he will respond one day to a request to have the church's hurtful stance explained, but it's really not likely," Ms Hingston said.
She said the church was determined to take away the basic rights of homosexuals.
"I am very much concerned that the separation of church and state is becoming less so," she said.
"We are frighteningly moving down the path of the USA, where religious fundamentalist leaders and Republican politicians run the country together."
The forum will be held on Sunday, September 12 at 7pm (AEST) at the Valhalla theatre in Glebe.
Cardinal Pell was not available for comment tonight.