Yes it is, Paul told them that in his first epistle, they were chosen and called 1 Cor 1:27-28
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;
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:
1 Cor 1 24,26
But unto them which are called, both Jews and Greeks, Christ the power of God, and the wisdom of God.
For ye see your calling, brethren, how that not many wise men after the flesh, not many mighty, not many noble, are called:
1 Cor 1:9
God is faithful, by whom ye were called unto the fellowship of his Son Jesus Christ our Lord.