Started playing yesterday, took care of the first demon. Today I wanted to continue... game starts from beginning.
No "Continue" option, only play. Don't remember, if there is a "continue" option, but I started the game several times, yesterday ... and I could always continue it, where I left.

Also: do I have to choose language every game start?! xD

I got a good hint on the steam forums. Let me quote a developer for the solution, respectively a workaround.

Hey Schlaumayr, there are easy ways to get your progression back, don't worry.
right click on The Blind Prophet in Steam, then Properties, then Local Data. Open the Local Data, you'll get a your folder with the game, the Data folder, and a Help txt. It will show you how to teleport to the place you were.

well.. thanks to play the beta tester, Schlaumayr..
That's why I Don't buy anymore adventure games day one !!
This game, black sad,... Jesus.....

Really Sorry for that, that shouldn't happen again.
We used a very specific way of managing the saves, we had to think of a special build technic to deal with it.
Let me know if that happens again at arsgoetiagames@gmail.com
See you!