Judge Mohammad Moghiseh refused to hear the case of Pastor Matthias Haghnejad, Shahrouz Eslamdoust, Babak Hosseinzadeh, Behnam Akhlaghi, Mehdi Khatibi until they agreed to replace their attorney.
The judge also refused to hear the case of four other members of the Church of Iran denomination who had decided to present their own defence.
Pastor Haghnejad and Mr Eslamdoust have been detained in Evin Prison in Tehran, while Mr Hosseinzadeh, Mr Akhlaghi and Mr Khatibi, who were transported to an unknown location, had their bail set at 160,000 Euros each.
The trial is set to resume in a few days on 28th July.
According to the Iran Prison Atlas, Judge Moghiseh - a cleric - has presided over the trials of many political prisoners and is iamous for having issued numerous death sentences.
Christian Solidarity Worldwide's Chief Executive Mervyn Thomas said: "This case highlights once again the lack of due process in Iran's Revolutionary Courts.
"The judge's arbitrary and unwarranted decision to punish these Christians, simply for wanting to be represented by a lawyer of their choice, constitutes a grave violation of article 14 of the International Covenant on Civil and Political Rights, to which Iran is party, and which stipulates, amongst other things, the right to legal assistance of one's choosing.
"We urge the Iranian authorities to ensure that the upcoming trial is both fair and transparent, and to end the policy of subjecting Christians, who merely seek to practice their faith peaceably, to excessive national security-related charges.
"We also urge the UK government and the EU to ensure that issues pertaining to freedom of religion or belief and other human rights are central to their dialogues with the Iranian government."
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