Previous answers have omitted the German (and Russian) language resources.
The German genealogy wiki page Bessarabia has large list of resources and links. The following paragraphs (translated to English) may be of interest:
...The church books (like all official documents) of Bessarabian German villages could not be removed in the resettlement of 1940 (according to the resettlement agreement). However, they were partly transferred in the subsequent recapture of Bessarabia in 1941 by German and Romanian troops to Berlin, where they were handed over to the Reichssippenamt. A detailed article on the whereabouts of Bessarabian church records can be found in the "Heimatkalender der Deutschen aus Bessarabien", 1993, pp.165-180.
Some of the church books from the territory of Bessarabia, belonging today to Moldova, are in the National Archives in Kishinev. The Church of Jesus Christ of Latter-day Saints (Mormons) in Salt Lake City has microfilmed copies of these documents. The Heritage Museum of the Germans from Bessarabia in Stuttgart has received copies from Kishinev.
About 350 original church register volumes and approximately 100 (filmed 1941 in Berlin) microfilms of church records documents from Bessarabia are available at the Deutschen Zentralstelle für Genealogie (German Central Office for Genealogy) in Leipzig. They are not complete, some are only a few years of family books or church events, such as baptisms, weddings, available. Detailed information is contained in the book "Die archivalischen...Kirchenbuchunterlagen deutscher Siedlungsgebiete...Bessarabien..." (full title in literature list later on page)