In section 16, Pope Pius XII looked to the Old Testament and the traditions of Israelite worship that kept God very much in the devotion of the Chosen People.
Section 17 outlines the life of the Lord on earth.
Today, we look at the post-Resurrection experience of God, founded through the Eucharist and the other sacraments, and maintained through long ages to today:
18. But it is His will, besides, that the worship He instituted and practiced during His life on earth shall continue ever afterwards without intermission. For he has not left (humankind) an orphan. He still offers us the support of His powerful, unfailing intercession, acting as our “advocate with the Father.”[Cf. 1 John, 2:1] He aids us likewise through His Church, where He is present indefectibly as the ages run their course: through the Church which He constituted “the pillar of truth”[Cf. 1 Tim. 3:15] and dispenser of grace, and which by His sacrifice on the cross, He founded, consecrated and confirmed forever.[Cf. Boniface IX, Ab origine mundi, October 7, 1391; Callistus III, Summus Pontifex, January 1, 1456; Pius II, Triumphans Pastor, April 22, 1459; Innocent XI, Triumphans Pastor, October 3, 1678]
Believers have the promise, the guarantee that God will always be with us. Perhaps that sustains us whenever we note the flaws in the human expression of worship, or when the struggle comes from within.
Consult Mediator Dei on the Vatican web site anytime for a wider perspective if you wish.