Believers
Acts 5:14 And believers were the more added to the Lord, multitudes both of men and women.)
1 Timothy 4:12 Let no man despise thy youth; but be thou an example of the believers, in word, in conversation, in charity, in spirit, in faith, in purity.
Brethren / Brother (Brethren in not in Scripture). Brother = A blood relative of the same mother. One of the same tribe, Of the same people, or even of a cognate people. An ally.
Occurs 109 times in the New Testament.
Christian
Acts 11:26 And when he had found him, he brought him unto Antioch. And it came to pass, that a whole year they assembled themselves with the church, and taught much people. And the disciples were called Christians first in Antioch.
Acts 26:28 Then Agrippa said unto Paul, Almost thou persuadest me to be a Christian.
1 Peter 4:16 Yet if any man suffer as a Christian, let him not be ashamed; but let him glorify God on this behalf.
Disciple
255 times in Matthew thru Acts. During Jesus’ earthly ministry, and during the days of the early church, the term that was used most frequently to designate one of Jesus’ followers was “disciple”. Hence, discipleship is a central theological theme of the Gospels and Acts.
But not in Paul’s letters.
Saints ⇛ also see Saints
Today, if you believe the Gospel (1 Corinthians 15:1-4) and Confess that Jesus is LORD (Romans 10:9-13)
You are a Believer, Brother, Christian, Saint……….. Mostly Saint.