What does he mean by "host"?
Host means (at a minimum) that you can work in the lab - the professor will provide space for you during the internship.
Does it mean funding?
It is ambiguous. This partially depends on what you asked for in your original letter asking for an internship.
How do I go on about asking him politely about it?
Being hired is ...
Don't feel bad. I'll assume that you had already earned the grade before you left. He may also have gotten some message about why you left and decided you had met the standard.
But it would be good, for many reasons, to send him an email with thanks and a bit of an explanation about your need to leave.
I once had a practice in a few courses that students ...
Germany maintains a list of accredited foreign universities from which degrees are recognized; you can find it on https://anabin.kmk.org/anabin.html . I would first advise you to check if your American university is there.
If your job is in the Biology department, it could simply be that an Economics degree does not count towards prior experience in the field and therefore doesn't raise your wage. That's at least how it works with full-time "Wissenschaftlicher Mitarbeiter" job positions.
Usual disclaimer: I am not a lawyer and this is not legal advice.
What the institute says is completely wrong: there is no such law.
The salary of Wissenschaftliche Hilfskräfte (HiWi, student doing scientific work) varies by state and by university, and it is not regulated by law. As explained in Chapters 3.3 and 6 of this document (unfortunately, ...
My experience with this sort of issue has been in teaching astronomy classes for gen ed students in which we deal with the Big Bang. In this context (which differs somewhat from yours), I think it's a good idea not to completely shut down questions about religion.
A student who is a business major may have very little understanding of how science works and ...
Many secular universities have theology faculty. You can suggest that your students ask them theological questions. This is the same as if I, a physicist, when asked about human perception of sound, suggested that students ask you.
You were correct in not engaging in religious argument in an academic setting. But a valid answer, that is probably acceptable to most people, whatever their faith, is, "I don't know. Your question is outside the realm of science."
If further asked, "What do you believe?", you can say that it is a private matter.
Unfortunately too many religious ...