Zanchi now proceeds to discuss festivals as applied to the Christian church in particular, by analogy with what he has already set out in relation to the Old Testament.
The Christian church, too, has festivals of both kinds: those instituted by direct divine warrant and those instituted by men with the consent of the people of God.
There is only one that belongs to the first class, namely, the first day of the week. Interestingly, Zanchi does not refer to this as the “Christian Sabbath,” but rather as the “Lord’s Day,” which is the successor to the Old Testament Sabbath, just as the Lord’s Supper is not referred to as the “Christian Passover,” but is the successor to the Old Testament Passover or Pascha. These are related to each other but are, at the same time, different in some fundamental ways.
Finally, Zanchi notes some patristic authorities that demonstrate the ancient practice of honoring the dies dominicus, the Lord’s Day.
Only one type of these (that is, one type of Christian festivals) has its origin from the apostles; the others have their origin from the fathers, but with the consent of the whole church. To the first type belongs the Lord’s Day, which was the successor to the Sabbath (Revelation 1: “I was in the Spirit on the Lord’s Day”). Why is it so called? As the Supper is called the “Lord’s Supper,” because it is the successor to the Passover, in the same way the “Lord’s Day” is the successor to the Sabbath; so also with respect to the circumcision of Christ, that is, baptism (Colossians 2), which is the successor to the Mosaic circumcision (2 Corinthians 16). Mention is made of this day (that is, the first day of the week) in Acts 20: “On the first day of the week, the brothers came together to break bread”; and Paul preached on that occasion. The fathers are witnesses of this practice: Justin Martyr in the Second Apology; 1 Tertullian in On the Soldier’s Crown and On Idolatry; Ignatius in To the Magnesians.[ref]The translation is my own.[/ref]