210 A correct understanding of the Church’s doctrine on the Saints is only possible in the wider context of the articles of faith concerning:
• the “One, Holy Catholic and Apostolic Church”(Roman Missal, Creed), Holy because of the presence in the Church of “Jesus Christ who, with the Father and the Holy Spirit, is proclaimed as the “sole Holy One” (John Paul II, Apostolic Constitution, Divinitus pefctionis magister, in AAS 75 (1983) 349); because of the incessant action of the Spirit of holiness (Cf. Lumen Gentium 4); and because the Church has been given the necessary means of sanctification. While the Church does have sinners in her midst, she “is endowed already with a sanctity which is real though imperfect”(LG 48); she is “the Holy People of God”(Cf. LG 48), whose members, according to Scripture, are called “Saints” (cf. Acts 9, 13; 1 Cor 6, 1; 16,1).
It is God’s action that inspires and gives the grace for saints. We believers are also sinners, but we can aspire to sainthood, can’t we?
• the “communion of Saints”(Symbolum Apostolicum, in DS 19) through which the Church in heaven, the Church awaiting purification “in the state of Purgatory” (Catechism 1472), and the pilgrim Church on earth share “in the same love of God and neighbor”(LG 49). Indeed, all who are in Christ and posses his Spirit make up a single Church and are united in him.
• LG 49
It is an old tradition that the Church extends beyond those living persons we might see. Makes sense, I suppose in light of a question: what happens to Christians when they die? Turn in a membership card? Likely not.
The Directory on Popular Piety and the Liturgy is online at the Vatican site.