A great many Lutherans are of German origin. The Missouri Syhod was founded by German immigrants, who left Germany because of their refusal to accept some sort of government-mandated unionism. In a manner much like many Lutherans of Norse ancestry, LCMS worship services were conducted in the language of their origins up to the 1940s, although offered as an alternative to English at that time and for some years prior. Missouri Synod Lutherans were frequently described in common parlance by other Lutherans as “the German church.”
I don’t know if the (currently ELCA) church I joined back in college was ever LCMS, but I know the old heritage church (where my grandparents just happened to elope) in the old town proper spoke/wrote in German up until about that time.