The earliest recorded marriage for the Territory of Wisconsin that I am aware of is January 1837. Wisconsin did not become a State until May 1848 when it was no longer under Territorial jurisdiction and formed its own state government. Green Bay (in Brown county) is considered the OLDEST city occupied by white settlers.
The Dheinsville church (now Village of Germantown, WASHINGTON county) has been disbanded for many years, however, if you click on this link:http://www.historyisfun.com/Church%20Records.htm
it will take you to the Washington County Historical Society Research Center page. They have copies of the Dheinsville church records which can be searched.
If I can be of further assistance please do not hesitate to contact me. --Carol