Question: "What is the G12 vision / movement?"
Answer: The G12 vision / movement is a cell-church discipleship strategy pioneered by Cesar Castellanos at International Charismatic Mission of Bogota, Colombia, where he was a pastor. Castellanos believed that God spoke to him in a vision, laying out what He desired the Church do in response to the end times. This vision was the “government of 12” principle, a hierarchal pyramid scheme of discipleship and authority. He proposed that because Israel had 12 tribes, and Christ had 12 disciples, the Church needed to base their structure on this governmental model and become a cell-church.
The G12 model works this way: a pastor trains 12 people to be cell leaders. These cell leaders are each responsible for discipling 12 others in a cell group, usually with a minimum number coming from the community and not from within the church they attend. After a specified time, and after certain strict requirements are met, these cell members then become leaders themselves, and start their own cells. Thus, the membership of the church is multiplied, and the message of the Gospel is taken into the community.
Obviously, there is nothing inherently wrong with this cell model. Churches worldwide are constantly seeking to discover the right balance of model and ministry to be effective in their communities, and this is yet another method they can use. However, the teachings that often accompany this model are what need to be questioned.
Consider Cesar Castellanos himself. Castellanos is part of the charismatic New Apostolic Reformation, which is doctrinally unsound. This movement believes that God has raised up present-day apostles to continue the work of the original apostles of Scripture and that these present-day apostles are in charge of overseeing the work of the Church on earth. They are associated with phrases such as "name it and claim it," the "Toronto blessing," "word faith," "signs and wonders," and "health and prosperity," all unbiblical teachings. Castellanos borders on believing that God gives them post-canonical revelation, including the G12 vision.
Leaders of the G12 movement have also made a number of questionable statements, such as, "The model of ministry based on 12 is the most effective means of obeying the Great Commission of Jesus Christ to win disciples and of growing the Church" (from a brochure for a G12 conference being held in India in 2003). Also implied by G12 leaders is that Government of 12 is what God is doing now, and that if you're not on board with G12 you are opposing God. None of this, however, can be supported by Scripture. Dividing a church into cells of 12 cannot even be supported by Scripture. What we do find in Scripture is that the Church is likened unto a body—many parts make up the whole, each part just as necessary as another (1 Corinthians 12). The Church is led by elders, served by deacons, and filled with believers. How each individual church is to govern and organize itself is left open to interpretation and supposition by Scripture.
The G12 vision / movement simply isn't found within the pages of the Bible, nor are many teachings its proponents espouse. This is where the true danger lies. As a church-growth model, G12 seems to have worked for many churches, but its association with doctrinally corrupt teachings leave much to be desired for those intent on retaining Scripture, and not man's teachings, as the sole measure for one's life (2 Timothy 3:15-16).