Paul uses different language to refer to Christians.
1. Brother/Sister. Paul recognizes these people as siblings under the Father, connected by the spirit of God. Jesus came to make us a family. For those persecuted for their faith, and lose their family, other believers are to step in to support them and be their new family. Include people and care for them.
2. Fellow Workers. Serve the Lord and the gospel. Use your gifts for the glory of God. We are all called to work hard for the kingdom of God because he is worthy.
3. Partners under Christ. Be reliable.
4. Fellow Soldier. While we must be responsible for daily issues we must also be mindful of the spiritual warfare that must be faced. Our wounds should reflect our engagement against the evil one.
5. Prisoner for Jesus. All who live righteously will suffer but it is our calling.
6. Saints. Anyone whom has been called and set apart for his purposes. We must also set apart time, money, energy for God.