BOZEMAN, Mont. — As a girl, Danna Hopkins dreamed of having 20 children. Today, she and her husband, Brian, the pastor of an evangelical church here, are building a large family, but not in the way she had imagined.

Ms. Hopkins gave birth to four children, now ages 7 to 11. A few years ago, inspired by compassion and a biblical mandate to aid “widows and orphans,” the couple adopted two teenage boys and a young girl from Ethiopia. Then in 2012, they adopted another girl from Ethiopia.

Last year, when they read about the dismal orphanages in the war-torn Democratic Republic of Congo, they started adoption proceedings for four young sisters whose parents, an agency said, had died of malaria and typhus.

“I believe it’s what God called us to do,” said Ms. Hopkins, 34.

She and her husband, and the Journey Church where he is lead pastor, are part of a fast-growing evangelical Christian movement that promotes adoption as a religious and moral calling. Its supporters say a surge in adoptions by Christians has offered hope and middle-class lives to thousands of parentless or abandoned children from abroad and, increasingly, to foster children in the United States as well. Hundreds of churches have established “orphan ministries” that send aid abroad and help prospective parents raise the tens of thousands of dollars needed to adopt.