A minister is by definition a servant. Each and every Christian is a minister, in this respect, and is given different and various gifts for performing their ministry.

"And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers; For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ."
Ephesians 4:11-12 (KJV)