Christians meet underground in a country where official churches do not exist.
The worshippers close their eyes, bow heads, hold hands, and speak their hopes and prayers out loud.
"I praise God for reconciling between my father-in-law and his stepdaughters.... Prayer works!" rejoices one. "I pray for ... the sanctity of marriage," says another.
"I give thanks for not being hit in the explosion today, and for suicide bombers staying away," a third intones, the sound of a chopper almost drowning him out.
"Amen," they sing, a group of men and women in neat camouflage fatigues, pistols strapped on their legs and chests and Bibles open in their hands.
And then there is Ahmed. With his acid-wash jeans, white shirt, and ID badge reading "escort required," he stands among them – mumbling the prayers, tapping his shiny brown loafers as the guitarist strikes up a catchy hymn. He's included, and apart, at the same time.
A recent convert to Christianity, Ahmed, who asked that his real name not be used out of fear for his security, has begun to join the hour-long church services at the Kabul Afghanistan International Airport (KAIA) base most Thursday evenings.
Even without consorting with Westerners, Afghan Christians face consequences for practicing their faith.
Months ago, Ahmed's parents, having discovered he had become a Christian, threw him out of the house, tossing his clothes into the street behind him. Later, they forced him into marriage with a relative from Kunduz, hoping this might return him to the ways of Islam.
His young bride, he admits, has no idea of the truth. She thinks he is at work. He leaves home, walking down the potholed Kabul road, boarding one bus, then another – always looking over his shoulder.
Converting to Christianity, punishable by death under Taliban rule, is no longer a criminal offense, but remains a highly risky choice in this conservative Muslim country. Just two years ago, the new Constitution notwithstanding, an Afghan man was sentenced to death for converting – and was only reprieved, on grounds of insanity, after a massive international campaign. He later went into exile.