WASHINGTON — Hundreds of advocates gathered Sept. 25 in Washington to pray for the release of U.S. minister Saeed Abedini, who has now been imprisoned in Iran for the past two years.

At the prayer vigil, Abedini’s wife read from a letter in which the imprisoned pastor reassured his 8-year-old daughter that “Lord Jesus Christ is in control” and expressed his wish that she “learn important lessons during these trying times,” particularly that “everything that is happening in it is for his good purpose.”

Born and raised as a Muslim in Iran, Abedini converted to Christianity in 2000, becoming an American citizen in 2010, following his marriage to his wife Naghmeh, who also is an U.S. citizen.

After his conversion to Christianity, Abedini began working with house churches in Iran. Although his work was technically legal, it drew complaints from the government, and he agreed to shift his work towards nonreligious humanitarian efforts.

While visiting nonreligious orphanages in September 2012, Abedini was arrested on charges of threatening national security. He was sentenced to eight years in prison; he has now served two years.

Human-rights groups following the case have claimed that the true reason for the imprisonment was the pastor’s Christian faith and his conversion away from Islam.

Both U.S. Secretary of State John Kerry and President Barack Obama have called on the Iranian government to release Abedini. Nearly 300,000 people have signed an online petition calling for his freedom.

At the vigil, Naghmeh thanked those present for “standing with us.”

She read from a letter sent by her husband to their daughter for her eighth birthday.

The imprisoned minister expressed his wish that he would be released soon, but told his daughter that even if he was not set free, they would sing Hallelujah together “either separated by prison walls or together at home.”

“So, let Daddy hear you sing a loud ‘Hallelujah’ that I can hear all the way here in the prison!” he said in the letter.

The Abedini children, Rebekkah and Jacob, then led the crowd in singing some of their father’s favorite hymns.

Also present was Rev. Franklin Graham, who was introduced as a spiritual adviser to the Abedini family.

The prayer vigil concluded with a prayer walk in front of the White House.

In addition to the D.C. event, more than 500 other prayer vigils in 33 countries around the world had been scheduled to recognize the pastor’s second year of imprisonment in Iran.

“We’ve asked you tonight to pray for Pastor Saeed and to pray for others who are imprisoned,” Franklin said, asking the crowd to “remember those who are persecuted for their belief,” particularly Christians.