While many are celebrating Christmas cozy at home with family and friends, Pastor Farshid Fathi is celebrating the birth of Christ away from his loved ones in a prison cell in Iran.

Fathi, who has now been four years behind bars, was arrested and detained in Tehran's Evin Prison in December 2010 for leading a network of underground evangelical house churches. He was later on found guilty of 'acting against national security' and sentenced to six years in prison.

But according to Miles Windsor, a London-based public affairs strategist who works on behalf of persecuted Christians in the Middle East, Fathi was convicted simply for being Christian in an Islamic country.

The 35-year-old father of two was born a Muslim but converted to Christianity when he was 17. Windsor wrote that being a Christian convert in Iran, wherein the official state religion is Shi'a Islam, is a dangerous thing.

Windsor stated in his Wall Street Journal article, "The mullahs reserve the most vicious treatment for Iranian Muslims, like Pastor Fathi, who have dared to convert to Christianity.

"Persian-language Bibles are banned in the country, and apostasy is punishable by death under Shariah law, which lies at the heart of the Iranian penal code.

"Yet to mask its naked persecution of Christian converts, the Tehran regime usually jails them on national-security charges or on the pretext that they spy for foreign powers."

In his opinion piece, Windsor also detailed the abuses that the Christian cleric endured in prison, including being one of several inmates who were beaten during an attack by security forces on Ward 350 of Evin.

Windsor added, "More recently, he was transferred to a different prison, Rajai Shahr, outside Tehran, where he shares a cell with hardened criminals.

"His right to family visits, guaranteed under Iran's own laws, is routinely violated. He isn't permitted to sing Christians hymns, and prison authorities have confiscated his Bible."

Fathi's supporters, who have created a Twitter and Facebook campaign calling for his release, and were holding a day of prayer for the pastor on the fourth anniversary of his detention.

They wrote in their most recent post, "God can do the impossible and secure an early release for this greatly loved man."

Fathi wrote in his most recent letter to his supporters, "Although the beauty of Christmas or the signs of Christmas cannot be found in this prison, with the ears of faith I can hear the everlasting and beautiful truth that: 'The virgin will conceive and give birth to a son, and they will call him Immanuel.'"

The pastor signed the letter "your captive brother who is free in Christ."