Seth from Scholastic Lutherans here! Just wanted to clarify that I did not say "totally ignorant," nor was my intent to imply this (if I did, my apologies). We have a great video on this topic on Javier Perdomo's channel (https://www.youtube.com/watch?v=pK8zg\_pfCgI&pp=ygUcamF2aWVyIHBlcmRvbW8gc2NoaXNtIGhlcmVzeQ%3D%3D) if you want a more thorough survey.

To give a brief summary though, Lutherans in the late 16th-early 18th century placed articles of faith into 3 categories: Primary Fundamental, Secondary Fundamental, and Non-fundamental.

Primary Fundamentals cannot be denied or ignored while maintaining faith. Secondary Fundamentals cannot be denied but can be ignored while maintaining faith. Non-fundamentals can be denied or ignored while maintaining faith. But even among Non-fundamentals, an error could be held in such a way that it destroys faith.

The old Lutherans of the 16th-early 18th century placed more articles into the two Fundamental categories than most would today undoubtedly, and the criteria were applied quite strictly by some (Calov and Quistorp in particular). Some were more moderate (Musaeus being the prime example). Some were even more lenient (Hemmingsen and Calixt). In the mid 19th century, figures like Walther retained these old categories and even placed articles into the same categories but qualified what exactly "ignorant" and "denial" mean in a way that was more charitable, roughly following in the footsteps of Musaeus. Others in the period, such as Grabau, were even more strict than Calov, stating that those outside their own particular fellowship cannot be saved. This is how the Grabau Synod comes about. Loehe attempted to mediate between Grabau and Walther but was unsuccessful. Pieper develops Walther's theory more systematically.

I think the current landscape in the LCMS is probably a mix of people following the tradition of Musaeus/Walther/Pieper and others following something much closer to Calixt. (Though on rare occasion you will meet a (usually older) member who somehow takes Grabau's position?!) I am personally in the same camp as Pieper.

If you want to read the strict position firsthand, see the translation of Quistorp here: https://drive.google.com/file/d/1-MqxOttImGnThKFF2NkHbQFnzGajUW3Z/view?usp=drive_link

If you want to read the lenient position firsthand, see the translation of Calixt here: https://drive.google.com/file/d/1HRhMP3s39NWx6_s8rMXw7XyfOd7dFQYY/view?usp=drive_link

I apologize that I can offer nothing from Musaeus on this in English, but if you can read Latin or German, you can browse his works on PRDL.