Answer: There are four reasons that come to my mind. The first is the need to obey the Great Commission of Christ. The second is the need to be accountable to the body of Christ. The third is the need to model the methodology of Christ. The fourth is the need to be conformable to the character of Christ. Let me unpack these.
The first reason why discipleship should be a major priority of the church is the need to obey the Great Commission of Christ. We are called to be obedient to the Great Commission as found in Mt. 28 : 19, 20. We demonstrate our love for the Lord to the degree of obedience to His Great Commission (John 14:23, 24). The Great Commission calls us to discipleship.
The second reason we should have discipleship as a priority for the church is the need to be accountable to the body of Christ. Fellow believers comprise the body of Christ. We demonstrate our body life by our willingness to be accountable to one another. Discipleship is one of the best ways in which accountable relationships can be lived out. Chuck Swindoll points out that: Lot was accountable to Abraham (Gen.13); Joseph was accountable to Potiphar (Gen.39); Saul was accountable to Samuel (I Sam. 13); David was accountable to Nathan (II Sam. 12); Nehemiah was accountable to the king (Neh. 1-2); Daniel made himself accountable to each king; Daniel was accountable to his peers (Dan. 1 -6); Jesus was accountable to God; the disciples were accountable to Jesus; John Mark was accountable to Paul and Barnabas; Timothy was accountable to Paul; Onesimus was accountable to Philemon, and Diotrephen was accountable to John as an elder. We should be accountable to whom He wants us to be, fellow Christians. The need to have accountable relationships in the body of Christ calls us to discipleship.
The third reason discipleship should be a priority for the church is the need to be modeling the methodology of Christ . We master our lessons by observing and by doing. Christ's methodology is discipleship. Robert Coleman in "The Master Plan of Evangelism", points out Christ's methods. Men were His method (Luke 6 :13). Those few and faithful who were willing to learn. He stayed with them over time (Matt. 28:20). He required that they count the cost of obedience knowing few would pay the price (Matt.11:29; Mark 8:34 -38). He gave Himself away (John 20:22). He showed them how to live (John 13:15). He delegated work to them (Matt. 4:19). He supervised their progress (Mark 8:17). He expected them to reproduce (John !5:16). His classroom teaches His methods and His way; the way of discipleship. Modeling the methodology of Christ calls us to discipleship.
Finally, discipleship should be a major priority of the church because of the need to be conformable to the character of Christ. Conformity to His character is key: following the Ten Commandments, exhibiting the nine fruit of the Spirit; demonstrating the eight Beatitudes; striving to obey the two greatest Commandments, to love God and to love our neighbor; responding in love to the great Commission. We can be encouraged, He who began a good work in us promises to bring it to completion (Phil. 1:6). He promises to change us daily (II Cor. 4:16-18),to become like He is. The need to be conformable to His character calls us to discipleship.
Therefore, discipleship should be a high priority for any church. Discipleship addresses four needs of any church; the need to obey the model the methodology of Christ; and finally, the need to be conformable to the character of Christ. These four reasons call us to discipleship as a high priority for any church.