Baptism reflects all three aspects of a disciple’s identity [rational, relational, and missional], with particular emphasis on missional. First, baptism is a sign that we have learned the gospel. It signifies our identification with Christ in his death as we are lowered into his “watery grave,” and identification with his life, where we are raised up into his resurrection life (Rom 6:4).
Second, we are baptized into two overlapping communities. The first is the divine community of the Trinity: “Baptizing them in the name of the Father and the Son and the Holy Spirit” (Matt 28:19). The second community is the church: “For in one spirit we were all baptized into one body” (1 Cor 12:13). Baptism results in a new spiritual family–the family of the Trinity.
Third, baptism is missional because it is the outcome of obedience to the Gospel Commission. If sent disciples don’t share the gospel in the power and authority of Jesus, then people don’t get to respond by repentance, faith and baptism.
In a sense, baptism is the end of the Gospel Commission and, at the same time, it is its beginning. Baptism begins our participation in wonderful gospel mission. Whenever someone is baptized, another disciple is sent in the power and authority of Jesus to join the mission of making disciples of all nations.
Jonathan K. Dodson, Gospel-Centered Discipleship (pg. 32-33).
So, first of all, Christians must be like their neighbors in the food they eat and clothes they wear, their dialect, general appearance, work life, recreational and cultural activities, and civic engagement. They participate fully in life with their neighbors. Christians should also be like their neighbors with regard to excellence. That is, Christians should be very good at what others want to be good at. They should be skillful, diligent, resourceful, and disciplined.
Second, Christians must be also unlike their neighbors. In key ways, the early Christians were startlingly different from their neighbors; it should be no different for us today. Christians should be marked by integrity. Believers must be known for being scrupulously honest, transparent, and fair. Followers of Christ should also be marked by generosity. If employers, they should take less personal profit so customers and employees have more pay. As citizens, they should be philanthropic and generous with their time and with the money they donate for the needy. They should consider living below their potential lifestyle level. Believers should also be known for their hospitality, welcoming others into their homes, especially neighbors and people with needs. They should be marked by sympathy and avoid being known as self-serving or even ruthless in business or personal dealings. They should be marked by an unusual willingness to forgive and seek reconciliation, not by a vengeful or spiteful spirit.
Timothy J. Keller, Center Church: Doing Balanced, Gospel-Centered Ministry in Your City (pg. 282-283).