Adiaphora are not worship of God, but can be used for good order, Christian discipline, and the Church's edification...

Regarding genuine adiaphora, or matters of indifference (as explained before), we believe, teach, and confess the following:  such ceremonies, in and of themselves, are not worship of God, nor any part of it.  They must be properly distinguished from ceremonies that are.  As it is written, "in vain do they worship Me, teaching as doctrines the commandments of men" (Matthew 15:9).

We believe, teach, and confess that the community of God in every place and every time has, according to its circumstances, the good right, power, and authority to change and decrease or increase ceremonies that are truly adiaphora.  They should do this thoughtfully and without giving offense, in an orderly and appropriate way, whenever it is considered most profitable, most beneficial, and best for good order, Christian discipline, and the Church's edification.  Furthermore, we can yield and give in with a good conscience to the weak in faith in such outward adiaphora.  Paul teaches this in Romans 14 and proves it by his example.
~BOC, FSD, X, 8-9

Preaching and faith are our daily sacrifice...

They also cite the daily sacrifice.  Just as there was a daily sacrifice in the Law,  so the Mass should be a daily sacrifice of the New Testament.  The adversaries have made out well if we allow ourselves to be overcome by allegories.  Clearly allegories do not produce firm proof.  We readily allow the Mass to be understood as a daily sacrifice, as long as that includes the entire Mass:  the ceremony with the preaching of the Gospel, faith, invocation, and thanksgiving.  Joined together, these are a daily sacrifice of the New Testament because the ceremony of the Mass, or the Lord's Supper, was set up because of these things.  The Mass is not to be separated from them.  So Paul says, "For as often as you eat this bread and drink the cup, you proclaim the Lord's death until He comes" (I Corinthians 11:26).  But it cannot be shown from this Levitical type that a ceremony justifying by the outward work (ex opere operato) is necessary, or should be applied on behalf of others, that it may merit the forgiveness of sins for them.

The type represents appropriately not only the ceremony, but also the preaching of the Gospel.  In Numbers 28:4-8, three parts of that daily sacrifice are represented:  the burning of the lamb, the drink offering, and the offering of wheat flour.  The Law had pictures or shadows of future things.  So Christ and the entire worship of the New Testament are shown in this picture.  The burning of the lamb illustrates Christ's death.  The drink offering illustrates that everywhere in the entire world, by the preaching of the Gospel, believers are sprinkled with the blood of that Lamb, that is, sanctified.  Peter says, "In the sanctification of the Spirit, for obedience to Jesus Christ and for sprinkling with His blood" (I Peter 1:2).  The offering of wheat flour means faith, prayer, and thanksgiving in hearts.  Therefore, in the Old Testament, the shadow is discerned.  In the New, the thing illustrated should be sought, and not another type, as sufficient for a sacrifice.

Although a ceremony is a memorial of Christ's death, it alone is not the daily sacrifice.  The memory itself is the daily sacrifice, that is, preaching and faith.  Faith truly believes that, by Christ's death, God has been reconciled.  A drink offering is required, that is, the effect of preaching, in order that, being sprinkled by the Gospel with the blood of Christ, we may be sanctified, as those put to death and made alive.  Offerings are also required, that is, thanksgiving, confession, and troubles.
~BOC, AP, XXIV (XII), 35-38