The Church is called the sacrament of Christ because it is a visible reality which Christ has formed in this world as a sacred sign of His presence. It is the sign and also the means He uses to give us the unity and holiness He actually confers through it. It is a sacrament of His presence because He is really present in it.
As a family called to share in the life of the Trinity, the Church has an eternal destiny. But in its time of pilgrimage on earth, it also has a visible, sacramental dimension: it exists also as a sign. Because the Church is a sign, it leads us to what it signifies, that is, to Christ, our God. When we finally come to God in eternity, the Church, as a material and time bound instrument of God’s will and grace, will have no further reason to exist. It will have accomplished what God put it on earth to do.
The sacrament, which is the visible Church, is now, in time, a precious indispensable gift of Christ. It is the work of Christ. It will last, as He promises, until the end of the world, when it will reach its fulfillment in glorious union in Christ. Its task on earth will not be finished until Christ brings His redemptive work to completion and God has become, as St. Paul put it, “all, and in all” (Colossians 3:11).