Thousands in Iran are becoming Christian and worshipping in homes hidden from view of the government, according to a ministry focusing on building Christian leaders in Iran.

According to the most recent numbers released by Open Doors USA, an estimate of some 450,000 are Christians in Iran, while other estimates say that the figure could be even higher, up to one million.

Several missionaries are being trained outside the country including from a London-based Pars Theological Centre which is fostering about 200 leaders to spread the gospel in Iran.

"Pars sees this as a real chance to train agents of change who would transform the Iranian society from the bottom up by fostering a grassroots development of the values of Jesus in an Iranian style. This is not a political movement at all, but it will have political implications because it is touching the core foundations of society ... It is not anti-Iranian. It's an Iranian movement. It's a great, great number of Muslims turning to Christ," a source told the Christian Post.

The center was founded by Rev. Mehrdad Fatehi in 2010, and has grown to 200 in three years, but is facing several challenges inside the church.

"While Iran's fast church growth is a cause for celebration, there is serious concern for the lack of depth in the movement and the severe shortage of well-equipped leaders to address this need. The church is facing a leadership crisis that, if not addressed, will damage its health and mission. So there is a great and urgent need for training quality leaders, and to do that there needs to be quality theological and leadership training that is accessible to those who are serving inside the country," the same source said.

The source further added that government persecution makes is difficult to assemble in groups of more than four to five.

The courses taught in the center range from Hermeneutics, Ministry and Teaching of Jesus, Apologetics, Christian Counseling, The Triune God, and The Suffering Church.

As many as 70 percent of the students enrolled in the center live in Iran, and study from offline video lectures and workbooks at their homes.