I am now able to advise how to access the parish books at Bern archives. Double click/tap the final catalogue entry to open where there is the pdf of each book.
Taufrodel = Baptisms
Eherodel = Marriages
Totenrodel = Deaths
At the end of the book is an index of sorts.
HOWEVER it’s all in German script so you will need to look on familysearch for their guide to reading it.
Zweisimmen is also available, and it’s not too far from Spiez, so a possibility.
I would highly recommend a visit to see the area...the Bernese Oberland is beautiful!