Romans 1:6
Among whom are ye also the called of Jesus Christ:
Under the New Covenant, not all men and women are the called of Jesus Christ. This called should not be confused with the called in Matt 22:14
14For many are called, but few are chosen.
There is a dispensational difference here, for under the Old Covenant Israel as a nation was called, and this is in reference to the nation as the context will tell, just read the passage leading up to that verse and that will be seen..
But in the NT post cross, the called are those that are the called of Jesus Christ, like Saul who became paul was called in Acts 9:1-6
So when writing His epistles and addressing them as the called, He has his personal experience to verify the calling he has in mind..
The called of Jesus Christ is not for all men, but for those men and women whom Jesus Christ was made sin for, and those whom His righteousness has been reckoned unto their account..
It is a distinct group of people, separated from all other peoples in the world..
It is a call that though it is to a distinct people, its inclusive of both jew and gentile per Rom 9:23-24
23And that he might make known the riches of his glory on the vessels of mercy, which he had afore prepared unto glory,
24Even us, whom he hath called, not of the Jews only, but also of the Gentiles?
It is the call to whom the eternal inheritance belongeth Heb 9:15
15And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance.
Here are more scriptures pointing out this distinguished group, the called:
1 Cor 1:23-24,26-28
23But we preach Christ crucified, unto the Jews a stumblingblock, and unto the Greeks foolishness
24But unto them which are called, both Jews and Greeks, Christ the power of God, and the wisdom of God.
Notice " but unto them which are called" in contrast to the stumbling jews and the worldly wise greeks"
But God has chosen ones [ the called] in both groups..
26For ye see your calling, brethren, how that not many wise men after the flesh, not many mighty, not many noble, are called:
The called are the same here as the chosen..
27 But God hath chosen the foolish things of the world to confound the wise; and God hath chosen the weak things of the world to confound the things which are mighty;
28 And base things of the world, and things which are despised, hath God chosen, yea, and things which are not, to bring to nought things that are:
The called: Rom 8:29-30
29 For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren.
30 Moreover whom he did predestinate, them he also called: and whom he called, them he also justified: and whom he justified, them he also glorified.
Not all are of the called of Jesus Christ, but only those given to Him for His seed, and they in due time are called into fellowship with Him.. 1 Cor 1:1,2,9
1Paul called to be an apostle of Jesus Christ through the will of God, and Sosthenes our brother,
2Unto the church of God which is at Corinth, to them that are sanctified in Christ Jesus, called to be saints, with all that in every place call upon the name of Jesus Christ our Lord, both their's and our's:
9 God is faithful, by whom ye were called unto the fellowship of his Son Jesus Christ our Lord.
This calling proceeds from the Faithfulness of God unto the chosen race, that seed whom Jesus died for..
Isa 53:10
10Yet it pleased the LORD to bruise him; he hath put him to grief: when thou shalt make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of the LORD shall prosper in his hand.
