A trial court in Iran has issued its final verdict, ordering a Christian pastor to be put to death for leaving Islam and converting to Christianity, according to sources close to the pastor and his legal team.

Supporters fear Youcef Nadarkhani, a 34-year-old father of two who was arrested over two years ago on charges of apostasy, may now be executed at any time without prior warning, as death sentences in Iran may be carried out immediately or dragged out for years.

It is unclear whether Nadarkhani can appeal the execution order.

“The world needs to stand up and say that a man cannot be put to death because of his faith,” said Jordan Sekulow, executive director of The American Center for Law and Justice (ACLJ).

“This one case is not just about one execution. We have been able to expose the system instead of just letting one man disappear, like so many other Christians have in the past.”

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It is also feared that Nadarkhani will be executed in retaliation as Iran endures crippling sanctions and international pressure in response to its nuclear agenda and rogue rhetoric. The number of executions in Iran has increased significantly in the last month.

“This is defiance,” Sekulow said. “They want to say they will carry out what they say they will do.”

The order to execute Nadarkhani came only days after lawmakers in Congress supported a resolution sponsored by Pennsylvania Rep. Joseph Pitts denouncing the apostasy charge and calling for his immediate release.

“Iran has become more isolated because of their drive for nuclear weapons, and the fundamentalist government has stepped up persecution of religious minorities to deflect criticism,” Pitts, a Republican, told FoxNews.com. “The persecuted are their own citizens, whose only crime is practicing their faith.”

The ACLJ has been a major driving force in keeping Nadarkhani’s case in the international spotlight. Many other advocacy groups and human rights organizations also have mounted global campaigns and petitions against the Iranian government, and experts credit Nadarkhani’s international support for keeping him alive.

The ACLJ recently launched a Twitter campaign to publicize Nadarkhani’s case, asking participants to dedicate a daily tweet to “Tweet for Youcef,” stating the number of days he has been imprisoned (currently 863) and ending the tweet with “ViaOfficialACLJ,” sending readers back to the organization’s website where they could learn more about his case.

Tweets have reached 157 countries and over 400,000 people.

Secretary of State Hillary Clinton and 89 members of Congress, along with the European Union, France, Great Britain, Mexico and Germany, have condemned Iran for arresting Nadarkhani and have called for his quick release.

Nadarkhani was arrested in October 2009 and was tried and found guilty of apostasy by a lower court in Gilan, a province in Rasht. He was then given verbal notification of an impending death-by-hanging sentence.

His lawyers appealed the decision under the premise that Nadarkhani was never a Muslim at the age of majority, and the case was sent to Iran’s Supreme Court, which upheld the lower court’s decision of execution, provided it could be proven that he had been a practicing Muslim from the age of adulthood, 15 in Islamic law, to age 19, which was when he converted.

The lower court then ruled that Nadarkhani had not practiced Islam during his adult life but still upheld the apostasy charge because he was born into a Muslim family.

The court then gave Nadarkhani the opportunity to recant, as the law requires a man to be given three chances to recant his beliefs and return to Islam.

His first option was to convert back to Islam. When he refused, he was asked to declare Muhammad a prophet, and still he declined.

Iran’s judiciary had delayed in issuing a final verdict, fearing the decision would have far-reaching political implications.

Sources say Nadarkhani has been advised by family members, lawyers and members of his church to remain silent throughout his ordeal, out of fear that authorities may use his statements against him, a strategy commonly employed by the regime.