"Inasmuch, then, as our churches dissent in no article of the faith from the Church Catholic, but only omit some abuses which are new, and which have been erroneously accepted by the corruption of the times, contrary to the intent of the Canons..."
- AC, Abuses Corrected
"...in order that it might be understood that in doctrine and ceremonies nothing has been received on our part against Scripture or the Church Catholic."
- AC, Conclusion
For the church to be "
Una Sancta " (the one Holy Catholic and Apostolic Church), these statements are
absolutely key and essential. "
Quod ubique, quod semper, quod ab omnibus creditum est " (that which has been believed everywhere, and always, and by all). If one insert new and novel doctrines, or eliminate that which has been believed from antiquity, that one is estranging himself (or herself) from the Church catholic, the Church orthodox.
Martin Luther's intent was not to create a new faith, but to eliminate the abuses that separated the Roman Church from the Church Catholic. Martin Chemnitz, David Chytraeus, Jakob Andrae, Martin Crusius, et al, carried on this noble torch. Holy Scripture even tells us how essential this "
Catholic principle " is. Just read Jesus' High Priestly Prayer (specifically John 17: 20-23 "perfected in unity"), and Paul's repeated calls for us to be of
one faith,
one doctrine (Romans 16:17, Ephesians 4:4-6, 2 Thessalonians 3:6, 1 Timothy 1:3 etc.). This
clearly refers to the eternal Church throughout all time... Each age, each "denomination" does not have the latitude to pick and choose what of the True and Ancient faith they want to believe. To pick and choose is the very meaning of the word heresy.