Metropolitan Paul Yazigi had no way to know that he was about to vanish into the chaos of the Turkish-Syrian border during the violent rise of the Islamic State.

"If we want to be good children to God, then we don't thank Him only when He gives us [blessings]," he said, in one of his final sermons (translated from Arabic) before he was kidnapped on April 22, 2013.

"Also, when we are hurting, we say to Him: 'Your hand must be taking care of us, and we thank You.' …A Christian is a creature that gives thanks to God for all things one knows and doesn't know, for both the good and the hardships one faces in his life."

Sermons about faith and suffering are always timely in ancient churches.

The bishops of Aleppo, Syria -- Metropolitan Yazigi and Metropolitan Yohanna Ibrahim of the Syriac Orthodox Church -- disappeared 10 years ago while seeking the release of two kidnapped priests. Their car was surrounded by a pack of armed men, as they maneuvered through risky checkpoints near west of Aleppo. Their driver died in the gunfire, but a survivor later testified that the kidnappers were not speaking Arabic and appeared to be from Chechnya.

There were no ransom demands from the terrorists. The shepherds of Aleppo simply vanished, inspiring few headlines outside the Middle East.

The 10-year anniversary passed quietly this spring, after years of special prayers during Orthodox worship services around the world.

"I don't think anyone can assume, at this point, that they are still living. But there is a sense that we don't know enough about what happened to have a sense of closure," said Father Thomas Zain, dean of St. Nicholas Antiochian Orthodox Cathedral in Brooklyn, New York.

"It's likely that they were kidnapped in Turkish territory, which added another level of complexity to the political situation." Many have concluded that the gunmen "didn't know who they had kidnapped. When they realized what kind of mistake they had made, they may have killed them immediately and moved on."

A joint statement from the two churches marking the anniversary was especially poignant since the leader of the ancient Antiochian Orthodox patriarchate is more than Metropolitan Yazigi's "brother" bishop -- they are actually brothers from the same family.

"Ten years have passed. As Christians, we continue to affirm that we are abiding here against all odds," noted Patriarch John of Damascus, in a statement written with Patriarch Ignatius Aphrem II, leader of the Syriac Orthodox Church.

"We have knocked on the doors of local and foreign governments, embassies and religious and civil authorities, in hope of receiving just a glimmer of hope. … Even now, we are determined with all our strength to discern what is factual in all the darkness enveloping this case, a case which involves the agonies of abduction and the humiliation of human dignity. This case calls for more than just sweet words about human rights."

It may be hard for outsiders to understand how events of this kind are both painful and tragically common for believers in churches born in the New Testament era, said Matthew Namee, editor of the Orthodox History website. The Book of Acts notes that "in Antioch the disciples were for the first time called Christians." The Antiochian Orthodox Patriarchate has, for centuries, been located in Damascus on the street called Straight.

"Antioch is, at its best, a bridge between competing cultures," said Namee, whose family roots are in Eastern Lebanon. "You just know that this region is always going to be highly contested. Add oil to the equation and there you go, raising the stakes even higher."

Armies from East and West have long fought to control this ancient crossroads defined by strategic waterways and trade routes linking three continents. In addition to Judaism, Christianity and Islam, the region contains a stunningly complex array of intertwined sects and other religious movements.

The mystery of the missing archbishops is now part of that never-ending drama.

"One thing leads to another, which seems to lead to another, and then it's one horror after another through the centuries," said Namee. "It's simply part of the history of Christian life in the Holy Land. … This is both tragic and inspiring. But the faith lives on, because the people keep believing."