'Faithful' in the Bible

To the saints and faithful brethren in Christ who are at Colossae: Grace to you and peace from God our Father.

just as you learned it from Epaphras, our beloved fellow bond-servant, who is a faithful servant of Christ on our behalf,

As to all my affairs, Tychicus, our beloved brother and faithful servant and fellow bond-servant in the Lord, will bring you information.

and with him Onesimus, our faithful and beloved brother, who is one of your number. They will inform you about the whole situation here.