The Church of England's teaching that marriage can only take place between a man and a woman is a "lousy definition" of matrimony, a bishop has said.
The Bishop of Buckingham Alan Wilson said the church's canon teaching "marriage is...of one man with one woman" was, in his words, "not much of a definition".
The bishop was speaking at the employment tribunal of Canon Jeremy Pemberton, who married his same-sex partner in a civil ceremony last year in defiance of guidance by Church of England bishops.
Mr Pemberton, the first member of the clergy to marry his same-sex partner, brought the case against Bishop Richard Neil Inwood, the former acting bishop for the diocese of Southwell and Nottingham.
The clergyman claims the bishop's decision to revoke his permission to officiate (PTO) as a priest in June 2014, and the refusing of a post for him as hospital chaplain in Nottinghamshire, breached the Equalities Act.
The church's case is that the issue of marriage between a man and a woman is enshrined in church doctrine.
Mr Pemberton's lawyers claim the issue is not one of doctrine, and that by his actions the bishop breached the law when he acted as he did.
The Bishop of Buckingham, appearing for Mr Pemberton, was asked by Thomas Linden QC, for the respondent Bishop Inwood, if he thought clergy "should accept the teachings of the church".
He replied: "Yes."
Asked about the church's teaching on "holy matrimony", he said: "It's not that I don't think it's true, or the canons of England should not be followed, all I say is it's a lousy definition, if it cannot tell you who is and who is not married."
The bishop, who is also an historian, said the reason that part of canon teaching was first included back in 1938 had little to do with the partnership being between a man and a woman.
He said the inclusion of marriage being between "one man and one woman" was "entirely coincidental because of the time it was framed".
The bishop went on: "They weren't making a doctrinal point but a statement about the position of marriage as it existed in that time, in 1938."
Mr Linden then asked: "Do you accept the clergy should accept the teachings of the church?"
The Bishop of Buckingham said: "Yes, but sometimes they don't do it very well.
"For example a divorcee may have difficulty teaching about marriage.
"That's just one example of how clergy might be limited in the doctrines they are expected to teach."
Earlier, the tribunal panel heard how Mr Pemberton had never been told about a Church of England press statement being drafted to explain his marriage to Laurence Cunnington in April 2014.
He told panel members a series of drafts, which went through the Archbishop of York's office, had never been shown to him and the first he saw of it was in a story about himself and his partner.
Mr Pemberton was asked by his own counsel Sean Jones QC: "Did anyone contact you to say they wanted to issue this press statement to assist you?"
"No," he replied, adding later: "I wasn't consulted."
The Church of England has defended its treatment of Mr Pemberton.
A spokesman said: "The Church supports gay men and women who serve as clergy in its parishes, dioceses and institutions.
"Jeremy Pemberton is one of many who currently serve and receive that support.
"The Church has no truck with homophobia and supports clergy who are in civil partnerships.
"The Church of England's doctrine on marriage is clear.
"The Church quite reasonably expects its clergy to honour their commitment to model and live up to the teachings of the Church.
"Clergy do not have the option of treating the teachings of the Church as an a la carte menu and only modelling those with which they personally agree.
"The Church is currently involved in a process of shared conversations about a range of issues on sexuality, in regions across the country.
"It is regrettable that this case risks undermining that process by invoking legislation which does not even apply to this situation."