Dear "Quincunx,"
If records from that period are still extant, they would probably not be housed at the church. I believe all the Seventh Day
Baptist churches transmit their historical records to the denominational Center in Janesville,
Wisconsin since they would be much better equipped than any church to protect and preserve historical documents. I don't remember the name of the currect Historian, but the Historian Emeritus is Rev. Don A. Sanford.
I noticed someone who also responded to your post suggested Arnold's Vital Record of
Rhode Island. To the best of my recollection Arnold did collect membership records from the First Hopkinton (Ashaway) Seventh-day
Baptist Church, but only through the late eighteenth or early nineteenth century. So that section, at least, of Arnold's collection wouldn't be much help to you, since you are looking for information from the MID nineteenth century.
Another compiler of
Rhode Island vital records was
Alden G. Beaman, who collected vital records from the century between 1760 and 1860. His compilation was published in eight or nine volumes.
Hope the above is helpful!