The Swenson Swedish Immigration Research Center has MANY microfilmed Swedish American church records, newspapers, etc. However, they don't have anything for Montcalm County.
Were John and Mary husband and wife?
Be aware that John could have been (and probably was) Johan, Johannes, Jon, Jöns, Jonas, and many other names which were Americanized to John.
Johnson could have been (and probably was) Johansson, Johannesson, Jonsson, Jönsson, Jonasson, and many other names which were Americanized to Johnson.
It is very unlikely (although possible) that he was named John and it is very unlikely (although possible) that his last name at the time of leaving Sweden was Johnsson.(with the possessive s)
Mary would have been Maria or Maja in Sweden. Unless her own father had a given name which could have been Americanized to John, she wouldn't have left Sweden using a form of Johnson. She would have used her own patronymic last name. She didn't suddenly stop being the daughter of her own father when she married. She remained his daughter her entire life, and her patronymic would tell what his given name was. It was not the custom for Swedish women to take on the patronymic last name of her husband after marriage, although they took on the U.S. name customs after arriving here.
These names are EXCEEDINGLY common. There are emigration indexes for Sweden but how can anyone distinguish between hundreds of possibilities without a birthdate?
Jönköping is a city in Sweden and it is also a county in Sweden. Records were kept in the parish and you need a parish name. Perhaps adding more detail to your query will help find the parish name.