I believe you are mixing the one invisible church of pure saints known only to God which exists without any division and the many visible churches which are known by their outward marks (what they teach).

I am not all-knowing. I can only judge the churches I have come in contact with. The Reform churches do not have the outward marks of pure doctrine. The reasons are given in previous threads. If you really believe Reform doctrine, you must reach the opposite conclusion. Namely, that Lutheran churches do not have the outward marks of pure doctrine and, therefore, are not true churches.