One in Christ and Heirs of Abraham

Galatians 3:28
New American Standard Bible 
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.

Sons Through Faith in Christ
…27For all of you who were baptized into Christ have clothed yourselves with Christ. 28There is neither Jew nor Greek, slave norfree, male nor female, for you are all one inChrist Jesus. 29And if you belong to Christ, then you are Abraham’s seed and heirs according to the promise.…

Cross References

Joel 2:29
Even on My menservants and maidservants, I will pour out My Spirit in those days.
John 17:11
I will no longer be in the world, but they are in the world, and I am coming to You. Holy Father, protect them by Your name, the name You gave Me, so that they may be one as We are one.
Romans 3:22
And this righteousness from God comes through faith in Jesus Christ to all who believe. There is no distinction,
Romans 3:29
Is God the God of Jews only? Is He not the God of Gentiles too? Yes, of Gentiles too,
Romans 8:1
Therefore, there is now no condemnation for those who are in Christ Jesus.
1 Corinthians 7:19
Circumcision is nothing and uncircumcision is nothing. Keeping God's commandments is what matters.
1 Corinthians 12:13
For in one Spirit we were all baptized into one body, whether Jews or Greeks, slave or free, and we were all given one Spirit to drink.
Galatians 3:14
He redeemed us in order that the blessing promised to Abraham would come to the Gentiles in Christ Jesus, so that by faith we might receive the promise of the Spirit.
Galatians 3:26
You are all sons of God through faith in Christ Jesus.
Galatians 4:14
And although my illness was a trial to you, you did not despise me or reject me. Instead, you welcomed me as if I were an angel of God, as if I were Christ Jesus himself.
Galatians 5:6
For in Christ Jesus neither circumcision nor uncircumcision has any value. All that matters is faith, expressed through love.
Galatians 5:24
Those who belong to Christ Jesus have crucified the flesh with its passions and desires.
Ephesians 1:1
Paul, an apostle of Christ Jesus by the will of God, To the saints in Ephesus, the faithful in Christ Jesus:
Ephesians 2:14
For He Himself is our peace, who has made the two one and has torn down the dividing wall of hostility
Ephesians 2:15
by abolishing in His flesh the law of commandments and decrees. He did this to create in Himself one new man out of the two, thus making peace
Philippians 1:1
Paul and Timothy, servants of Christ Jesus, To all the saints in Christ Jesus at Philippi, together with the overseers and deacons:
Colossians 1:4
because we have heard about your faith in Christ Jesus and your love for all the saints--
Colossians 3:11
Here there is no Greek or Jew, circumcised or uncircumcised, barbarian, Scythian, slave, or free, but Christ is all and is in all.
1 Timothy 1:12
I thank Christ Jesus our Lord, who has strengthened me, that He considered me faithful and appointed me to service.
2 Timothy 1:1
Paul, an apostle of Christ Jesus by the will of God, according to the promise of life in Christ Jesus,

Ellicott's Commentary for English Readers

(28) This verse continues the proof that all Christians are, in the fullest sense, "sons of God." Galatians 3:27showed why this was so; the present verse shows that there are no exceptions, no inequalities. All Christians alike, no matter what their race, status, or sex, stand on the same footing of sonship before God. There is a unity or solidarity in the Christian body. What is true of one is true of all.

Greek.--The spread of the Greek race through the conquests of Alexander, their ubiquitous presence, and the use of the Greek language as a universal medium of communication, led to the name "Greek" being applied to all who were not Jews. "Jew and Greek" is intended to be an exhaustive division of the human race, just as "bond or free," "male and female."

This verse marks the immense stride made by Christianity in sweeping away the artificial distinctions which had been the bane of the ancient world, and prevented any true feeling of brotherhood springing up in it. Christianity, at one stroke, established the brotherhood and abolished the distinctions.

One.--The word "one" is masculine--"one man," "a single person"--as explained in the paraphrase above.

Pulpit Commentary

Verse 28. - There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female (οὐκ ἔνι Ἰουδαῖος οὐκ ἔνι ἄρσεν καὶ θῆλυ); there is no dew here nor Gentile (literally, Greek), there is no bond man here nor freeman, there is not here male and female. The word ἔνι, occurring also in 1 Corinthians 6:5(according to the now accepted reading); James 1:17; Ecclus. 37:2; and very noticeably in Colossians 3:11, is probably (see Winer's 'Gram. N. T.,' § 14, 2, 'Anm.') an adverbialized form of the preposition ἐν, of the same description as the thus accented πάρα and ἔπι. The prepositional element implies a somewhat indefinite indication of a sphere in which the statement of the clause holds good. The Revised Version renders, "there can be," and Bishop Lightfoot, "there is no room for;" but Ecclus. 37:2 and 1 Corinthians 6:5 do not much favour this particular modification. In Colossians 3:11 we have a very similar passage; there, after describing Christians as "having put on (ἐνδυσάμενοι) the new man, which is being renewed unto knowledge after the image of him that created him," the apostle adds, "Where there is not Gentile [Greek, 'Greek'] and Jew, circumcision and uncircumcision, barbarian, Scythian, bondman, freeman; but Christ is all [literally, 'all things'] and in all." We may group with them also 1 Corinthians 12:12, 13, "So also is Christ; for in one Spirit were we all baptized into one body, whether Jews, whether Gentiles [literally, 'Greeks'], whether bondmen, whether freemen." In all three of these passages we see the reference both to "Jew and Gentile" and to "bondman and freeman." The particular mention of these two forms of outward classification was suggested by the circumstances of the Christian Church generally at that time. Wherever the apostles went, they were sure to be confronted by questions and difficulties arising both from the one and from the other. In the kingdom of God were Jew and Gentile, were circumcised and uncircumcised, to stand on the same footing? Should believers as such be concerned to vary their treatment of one another or to modify their own condition from regard to these circumstances? Questionings of this description were being agitated everywhere, and most especially just now in the Galatian Churches. And, on the other point, the universal existence of slavery more or less throughout the civilized world would necessarily give occasion to a variety of questions relative to the position which bondmen should hold in the Christian community; how a bondman on becoming a Christian should stand, or what he should do, in respect to obedience to his owner or to seeking a change in his condition. St. Paul, in his Epistles, has briefly discussed some of these points, as in 1 Corinthians 7:20-24; Ephesians 6:5-9. So often had the apostle occasion to affirm the perfect identity of Christian privilege possessed by all believers in Christ, that the statement would naturally mould itself into a sort of formula. In Colossians he varies the form by inserting "barbarian, Scythian;" degrees of national civilization made no difference. In place of this, he here adds the particular, that diversity of sex made no difference. We cannot tell what especial reason he had for introducing these modifications in writing to the Colossians and the Galatians respectively. Possibly he had none beyond the pleasure which he felt in dilating on the large catholicity of the Divine grace. In the clause, οὐκ ἔνι ἄρσεν καὶ θῆλυ, "there is here no male and female," the neuter is used (remarks Alford) as being the only gender which will express both. The change of form, "male and female," from "no Jew nor Gentile," "no bondman nor freeman," was perhaps suggested by the passage in Genesis 1:27(ἄρσεν καὶ θῆλυ), "male and female created he them," which is quoted in Matthew 19:4; Mark 10:6. If so, the clause may be regarded (as Bishop Lightfoot says) as forming a climax: "even the primeval distinction of male and female." But perhaps the change is simply made for the sake of variety; as in the way in which several of the classes are introduced in the Colossians. For ye are all one in Christ Jesus (pa/nte ga\r u(mei = ei = ἐστὲ ἐν Ξριστῷ Ἰησοῦ); for all ye are one and the same man in Christ Jesus. The pronoun ὑμεῖς, ye, is inserted to recite emphatically the qualification already expressed; as if it were, "ye being what ye are, believers baptized into Christ." The apostle's object here is not, as in 1 Corinthians 12:13; Colossians 3:11-15, to exhort to the performance of certain mutual duties on the ground of the unity which in Christ is established among all believers, but to enforce the view that each individual's title to the inheritance is altogether irrespective of external distinctions, and is based entirely, in one case as well as in another, upon his being clothed with Christ. The word εῖς is "one and the same," as in τὸ ε{ν φρονοῦντες, "of one mind" (Philippians 2:2); and in εῖς Θεός, εῖς μεσίτης, "One and the same God, one and the same Mediator" (1 Timothy 2:5). So Chrysostom: "That is, we have all one form and one mould, even Christ's. What," he adds, "can be more awful than these words? He that was a Greek, or Jew, or bondman yesterday, carries about with him the form, not of an angel or archangel, but of the Lord of all, yea, displays in his own person the Christ." The distribution of the universal quality to each individual, so far as the grammar of the sentence is concerned, is imperfectly expressed. But the grammatical inadequacy of the verbal exposition is not greater than in 1 Corinthians 6:5, "Decide (ἀνὰ μέσον τοῦ ἀδελφοῦ αὐτοῦ) between his brethren," literally, "between his brother;" and in vers. 19, 20 of the same chapter, σῶμα ὑμῶν, "your body;" not "thy body," nor "your bodies." The apostle has in view the subjective application only of the principle here stated; each was to feel that, having the qualification which he has explained, he himself is a son of God and full inheritor, without casting about for any further qualification, as, for example, from ceremonial Judaism. The principle plainly is pregnant with an objective application also; namely, as to the manner in which they were to estimate and treat each other and every baptized believer, notwithstanding any circumstances of extrinsic diversity whatever. 

Galatians 3:28 Commentaries