Ewan Aitken, executive member for education on the city council, threw his weight squarely behind the move and said all denominations were in favour.
Mr Aitken, who is also a Church of Scotland minister, said: "The two schools have shared common ground for many years."
He added: "I believe that shared campuses are a very good thing for education. As was said elsewhere this week, it is about celebrating difference."
In an article in the Church's magazine Life and Work last year, Mr Aitken said shared campuses were not only good for education but for ecumenism, eradicating sectarianism and bringing the churches closer together.
He made it clear that he does not support moves towards shared campuses because of any belief that separate Catholic schools are the cause of today's sectarianism. "These are attitudes nurtured as festering sores outside the education system, not from within it," he wrote.
Mr Aitken, who is education spokesperson for the Convention of Scottish Local Authorities, said that it was up to the churches "to break bread together in worship" if the root causes of sectarianism are to be eradicated.