All Are One in Christ
The FSB: Paul emphasizes that the standard categories that often divide people—race, social status, gender—do not apply to those who are in Christ. It is not that such criteria cease to exist; rather, these distinctions are not grounds for exclusion from the life that God offers to all people in Christ.
MacArthur writes: all those who are one with Jesus Christ are one with one another. This verse does not deny that God has designed racial, social, and sexual distinctions among Christians, but it affirms that those do not imply spiritual inequality before God.
Wiersbe adds: this does not mean that our race, political status, or gender is changed at conversion; but it does mean that these things are of no value or handicap when it comes to our spiritual relationship to God through Christ. The Law perpetuated these distinctions, but God in his grace has declared all men to be on the same level that he might have mercy on all men (Romans 11:25–32).
Galatians 3:28New American Standard Bible: 1995 Update
There is neither Jew nor Greek, there is neither slave nor free man, there is neither male nor female; for you are all one in Christ Jesus.