'Brother' in the Bible

Paul, an apostle (special messenger, personally chosen representative) of Christ Jesus (the Messiah) by the will of God, and Timothy our brother,To the church of God which is at Corinth, and to all the saints (God’s people) throughout Achaia (southern Greece):

my spirit could not rest because I did not find my brother Titus there; so saying goodbye to them, I left for Macedonia.

And we have sent along with him the brother who is praised in the gospel [ministry] throughout all the churches;

We have sent with them our brother, whom we have often tested and found to be diligent in many things, but who is now even more diligent [than ever] because of his great confidence in you.

I urged Titus to go, and I sent the brother with him. Titus did not take advantage of you, did he? [No!] Did we not conduct ourselves in the same spirit and walk in the same steps? [Of course!]