This misses the point, of course. The point is an attitude adjustment which may or may not entail worshiping the Lord together with a different denomination. Believe it or not, Luther did not want a “second denomination.” He wanted to get rid of the idea of denominations.
Considering that Jesus said he was founding a Church, which would never teach error, and which would exist until the end of the world, it seems highly probable that somewhere in the world right now there is the Church Jesus founded. Since that Church would enjoy the infallibility Jesus promised, it follows that no church that does not claim that infallibility could be the one Jesus founded.