Because Jesus commands us to disciple all the peoples.
When Jesus said, in Matthew 28:19, "Go therefore and make disciples of all the nations," the word translated nations is the Greek ethne, the basis for our word ethnic. It is not a political or geographical unit, but a people or tribe, defined by culture and language. God wants all ethne discipled. We focus on reaching ethne because they are God's focus and He commissioned us to reach them. Adoption is a means to help us do this. By unreached people, we do not refer to one’s unsaved neighbor, but on those cultures which have no witness in their own language. To "adopt" means to commit to the people until there is a viable, reproducing church planted among them.
Because unreached people haven't heard the gospel in their "heart"
To adopt an unreached people is to focus on one particular people who have had little or no access to the gospel of Jesus Christ in a language they understand. An unreached people is "a pocket of humanity" which has no existing native church in its midst. An unreached people is comprised of individuals who speak a common language and share a distinct culture, which often form barriers preventing the penetration of the gospel. The Iranian community of 400,000 in Los Angeles, because of their language and cultural differences are an unreached people, as are the 120,000 Kalanga of Botswana and the 10,000 Lowland Semang in Indonesia.
Because we have the resources.
The International Journal of Mission Frontiers (October 1990) states that, an unreached people is "a people group among which there is no indigenous community of believing Christians with adequate numbers and resources to evangelize this people group without requiring outside (cross-cultural) assistance." They need others who will learn their language and culture in order to share with them the gospel in an understandable and acceptable way. With the resources available to us, we can send and support those who go (who we call 'missionaries'). Adoption helps us be good and effective stewards. Many resources are available to help. One place to start is the AD2000 WEB site (http://www.ad2000.org), which includes data on the largest ethno-linguistic peoples (The Joshua Project 2000 Peoples). The Adoption Guidance Program will help with each aspect of adoption and points toward many other resources and agencies.
Because you and your church will be blessed.
"The Lord had said to Abram, "Leave your country, your people and your father's household and go to the land I will show you. I will make you into a great nation and I will bless you; I will make your name great, and you will be a blessing. I will bless those who bless you, and whoever curses you I will curse; and all peoples on earth will be blessed through you." (Gen. 12:1-3) Adoption is a way to participate.
Because adoption into God's family is biblical.
Adoption is effective because it is patterned after God, who is calling and adopting sons and daughters from every tribe, tongue and nation, "He predestined us to adoption as sons through Jesus Christ to Himself, according to the kind intention of His will" (Ephesians 1:5). When we adopt a people, we are His agents or ambassadors.
Because adoption is an effective way to reach the world.
Adoption is effective because it makes sure that every people has a group of Christians praying for and reaching out to them. Adopting a people is a "doable" piece of the Great Commission, where each church, large or small, can play a part. Within many countries there are peoples who have no witness in their language or culture. People adoption focuses primarily on the goal of reaching the people, rather than only on the means.
Through adoption, the goal of a church for every people becomes achievable. Some researchers believe there are at least 3,000 evangelical churches for every Joshua Project 2000 people. God has already hidden each people in His heart and seeks to adopt them into His family. In people adoption, we act as His agents to welcome our brothers and sisters home, into the relationship which God, in Christ, prepared for them. With churches focusing on different unreached peoples through adoption, all peoples may receive access to the gospel. The adoption strategy provides the vehicle for Christian groups to become deeply involved in finishing the task.