Pastors Behnam Irani and Matthias Haghnejad, and Deacon Silas Rabbani, who had earlier had capital charges against them dropped, each received six-year sentences in October.
They are accused of "action against the state" and "action against the order".
In court their lawyer Moshkani Farahani, who had previously argued against the charges faced by each of his clients at the last court session of this trial on 24 November, said they should be released.
During the previous session, Mr Farahani argued that it was inconceivable that Behnam Irani could have been guilty of the political crimes given that he was already imprisoned.
He went on to state that Matthias Haghnejad should be released on the basis that he had previously been acquitted of charges by a tribunal in Bandar-Anzali.
Mr Farahani also contended that people cannot be sentenced on political charges for simply belonging to a religious fellowship.
He told the court: "It is normal for members of minorities to be in touch with each other; Jews are in touch which others, Zoroastrians are in touch with each other, it is the same for Assyrians, Orthodoxes and Evangelicals. Such connections cannot be perceived as a penal crime."
Christian Solidarity Worldwide Chief Executive Mervyn Thomas said, "The charges faced by Pastors Behnam Irani, Matthias Haghnejad and Deacon Silas Rabbani are clearly unjust, as Mr Farahani has argued in court.
"We continue to call on the authorities to release these clergymen along with Ebrahim Hosseinzadeh, unconditionally and without delay.
"Their only 'crime' is to exercise their right to freedom of religion or belief, as guaranteed in the International Covenant of Civil and Political Rights, to which Iran is signatory.
"We urge the Iranian government to uphold this right for religious minorities in Iran, in line with its obligations under international law and the provisions upholding the rights of religious minorities in its own constitution."