What does canonisation mean? Is there a two-tier society in heaven?
The “Catechism of the Catholic Church” comments on the call to sainthood, which is linked with the call of a person to Baptism, and on the meaning of canonisation in the following paragraphs:
“824 United with Christ, the Church is sanctified by him; through him and with him she becomes sanctifying. "All the activities of the Church are directed, as toward their end, to the sanctification of men in Christ and the glorification of God." (Sacrosanctum Concilium 10). It is in the Church that "the fullness of the means of salvation" has been deposited. (Unitatis reintegratio 3)It is in her that "by the grace of God we acquire holiness." (Lumen Gentium 48)
825 "The Church on earth is endowed already with a sanctity that is real though imperfect." (Lumen Gentium 48). In her members perfect holiness is something yet to be acquired: "Strengthened by so many and such great means of salvation, all the faithful, whatever their condition or state - though each in his own way - are called by the Lord to that perfection of sanctity by which the Father himself is perfect." (Lumen Gentium 11).
826 Charity is the soul of the holiness to which all are called: it "governs, shapes, and perfects all the means of sanctification." (Lumen Gentium 42). […]
827 'Christ, holy, innocent, and undefiled,' knew nothing of sin, but came only to expiate the sins of the people. The Church, however, clasping sinners to her bosom, at once holy and always in need of purification, follows constantly the path of penance and renewal." (Lumen Gentium 8). All members of the Church, including her ministers, must acknowledge that they are sinners. In everyone, the weeds of sin will still be mixed with the good wheat of the Gospel until the end of time. Hence the Church gathers sinners already caught up in Christ's salvation but still on the way to holiness: […]
828 By canonizing some of the faithful, i.e., by solemnly proclaiming that they practiced heroic virtue and lived in fidelity to God's grace, the Church recognizes the power of the Spirit of holiness within her and sustains the hope of believers by proposing the saints to them as models and intercessors. "The saints have always been the source and origin of renewal in the most difficult moments in the Church's history." (Christifideles Laici 16,3). Indeed, "holiness is the hidden source and infallible measure of her apostolic activity and missionary zeal. (Christifideles Laici 17,3)."
829 "But while in the most Blessed Virgin the Church has already reached that perfection whereby she exists without spot or wrinkle, the faithful still strive to conquer sin and increase in holiness. And so they turn their eyes to Mary" (Lumen Gentium 65): in her, the Church is already the ‘all-holy’."