The churches have decided not to apply for the medium wave "Religious" radio licence for Dublin, recently advertised by the Independent Radio and Television Commission.
Speaking at the Dublin and Glendalough Church of Ireland synods in Dundrum, Dr Kenneth Milne said the churches had decided against applying because they believed that on the medium wave they would not reach a significant number of those with whom they wanted to communicate.
A letter had been written to the IRTC explaining the churches' position, he said.
The Communications Officer for the Dublin (Catholic) archdiocese, Father John Dardis, said he was "disappointed the IRTC decided not to open FM to a religious station".
The Churches' Radio Consultation Group, which had been exploring the possibility of applying for a licence, had expressed this disappointment to the IRTC, he said. They had also said that should another FM licence become available they would be interested.
The key factor in the churches' expression of interest in a radio licence was their desire to take part in the dialogue shaping modern Ireland and in being part of the dialogue between faith and culture. "Obviously FM is where that can occur," he said.
The Radio Consultation Group is made up of Catholic and Church of Ireland representatives, as well as representatives of six religious orders. The group is also in discussion with both the Presbyterian and Methodist churches.
It had hoped to secure an FM licence to broadcast to the 1.1 million potential listeners in the greater Dublin area, and had planned to broadcast from studios at Maynooth.
Father Dardis said the Radio Consultation Group would continue in existence to explore other ways of taking part in broadcasting, "possibly with the existing Dublin stations".