CCC 775 “The Church, in Christ, is like a sacrament – a sign and instrument, that is, of communion with God and of unity among all men.”¹ The Church’s first purpose is to be the sacrament of the inner union of men with God. Because men’s communion with one another is rooted in that union with God, the Church is also the sacrament of the unity of the human race. In her, this unity is already begun, since she gathers men “from every nation, from all tribes and peoples and tongues”;² at the same time, the Church is the “sign and instrument” of the full realization of the unity yet to come.

CCC 1138 “Recapitulated in Christ,” these are the ones who take part in the service of the praise of God and the fulfillment of his plan: the heavenly powers, all creation (the four living beings), the servants of the Old and New Covenants (the twenty-four elders), the new People of God (the one hundred and forty-four thousand),³ especially the martyrs “slain for the word of God,” and the all-holy Mother of God (the Woman), the Bride of the Lamb,⁴ and finally “a great multitude which no one could number, from every nation, from all tribes, and peoples and tongues.”⁵

1 LG 1.
2 Rev 7:9.
3 Cf. Rev 4-5; 7:1-8; 14:1; Isa 6:2-3.
4 Rev 6:9-11; Rev 21:9; cf. 12.
5 Rev 7:9.