But since they speak german, were luteran and all the documents that I had found are in the germany, maybe this can proof that they were German.

I don't think so. Most of the German settlers in Volhynia were Russian subjects, otherwise they weren't allowed to buy land, for example. A lot of families had settled in Congress Poland for decades before coming to Volhynia.

It is true that some Germans in Volhynia were Prussian subject but they had come directly from Prussia to Volhynia - and your ENGELs did not.

Einbürgerungurkunde

You might find such a certificate if August ENGEL did apply for German citizenship. The records could be at Berlin in "Geheimes Staatsarchiv Preußischer Kulturbesitz".
https://www.gsta.spk-berlin.de/

Carlos Cesar Hennig from Brasilia could probably give you some advice on this. Go to one of his postings and you can send him a message by clicking the envelope icon next to his name.
https://forum.wolhynien.de/index.php?id=26539

August ENGEL was born 21 Jul 1887 in Janowka, Rozyszcze parish.
http://agadd.home.net.pl/metrykalia/439/sygn.%2012/pages/PL_1_439_12_0141.htm

He had brothers and sisters, all born in Janowka to parents Johann ENGEL and Emilie RESCHKE:
Gustav *1886 +1886
August *1887
Reinhold *1889
Rosalie *1892
Bertha *1895
Alma and Natalie *1897 (twins)

Johann ENGEL and Emilie RESCHKE got married in 1884.
http://agadd.home.net.pl/metrykalia/439/sygn.%2042/pages/PL_1_439_42_0101.htm

The church books are in the Central Archives of Historical Records in Warsaw (AGAD). To get the records certified you will need to get in touch with the archives.
http://agad.gov.pl/?page_id=904

However, all this will not prove that they were German, since August ENGEL was born in Volhynia Governorate in Russia and his parents are both from Piotrków Governorate in Congress Poland. Did August ENGEL ever apply for German citizenship before going to South America?

Irene

I am doing a geneology reaserch and I found out that my german family are from Janowka, in the Wolhynien region.

I already have this film of the birth certificate/batism of my great grandfather, August Engel, but this has no value for my German nationality request.

So, I need your help. Where I can request a "real" Birth Certificate of someone who was born in this region? Because I have not found the Registry of Janowka.