Pastor Yousef Nadarkhani (pictured) and his members were arrested during a series of house raids by security service personnel in the northern city of Rasht in May, and accused acting against national security.
Chief Executive of Christian Soldiary Worldwide, an organisation working for religious freedom, Mervyn Thomas said: "The spurious national security-related charges levelled against these men are illustrative of a continuing campaign by the authorities to penalise the Christian community for peaceably exercising the right to freedom of religion or belief. "
Pastor Nadarkhani, Yasser Mossayebzadeh, Saheb Fadaie and Mohammed Reza Omidi (Youhan) are due back in court on Wednesday 14th December 2016.
Meanwhile, Mossayebzadeh, Fadaie and Omidi are also expected to attend a hearing at the 11th Branch of the Appeal Court in Iran as they challenge sentences of 80 lashes for drinking wine during a communion service.
CSW's Mervyn Thomas went on to say: "We are alarmed by the rising repression and the renewed targeting of Pastor Nadarkhani and members of his church.
"We also reiterate that the criminalisation of a significant Christian sacrament should not be occurring in a country where the constitution not only recognises Christianity, but also states that no-one should be molested or taken to task on account of their belief.
CSW is also warning that the situation for Iranian Christians has "deteriorated markedly", illustrated by a wave of arrests and harassment, and a rise in restrictions on freedom of religion or belief.
Thomas added: "We call on the Iranian Government to ensure these men receive a fair hearing, and urge the dismissal of these charges.
"The international community must press Iran to ensure religious freedom for all of its citizens, and that its practices, legal procedures and provisions are in line with its constitutional and international commitments to uphold freedom of religion or belief, including the right to change belief, for every religious community."