The following site states where you can write for the records for the church at Gross Sabow:

Landeskirchliches Archiv der Pommerschen Evangelischen Kirche
Rudolf-Petershagen-Allee 3
D-17489 Greifswald
Germany
Email address: archiv@pek.de
Contact: Diplomarchivarin Ulrike Reinfeldt

Here is the website for the archives:

www.pommersches-kirchenarchiv.de/

One important bit of information you should note is that only about 17% of church registers in Hinterpommern (that area of Pommern east of the Oder River and now in Poland) survived World War II. You are indeed very fortunate that the records for the church at Gross Sabow, Kreis Naugard, have survived. Please note the hours and days the archives is open, if you plan to visit.

Groß Sabow records are on microfilm and they have the following records available:

1708-1766 Baptisms, marriages & deaths
1766-1772 Baptisms
1767-1772 Marriages
1766-1772 Deaths
1773-1829 Baptisms, marriages & deaths
1773-1829 Confirmations
1830-1835 Baptisms, marriages & deaths
1830-1856 Confirmations
1836-1847 Baptisms, marriages & deaths
1848-1885 Baptisms, marriages & deaths
1886-1942 Baptisms
1886-01/1945 Marriages
1886-1944 Deaths
1901-1930 Confirmations
1931-1944 Confirmations
1942-01/1945 Baptisms

Congratulations on being one of the very few fortunate people who may find your Hinterpommern ancestors. Civil registration began in 1874 and I would direct any questions about those records to the Archives.

And be prepared for variations in the spelling of Jahnke. There are about 5 different ways to spell it.

Cary C.