Unternehmer is not straightforward. 'Entrepreneur' implies someone who is very dynamic and builds up their own business (e.g. Richard Branson is an entrepreneur, the general manager of a small local business is not).

'Businessman' is fine, if you don't mind possibly being accused of being sexist. 'Businessperson' gets around that problem, but is a bit cumbersome. It all depends on what the speech goes on to talk about.

Perhaps: 'Economics and ethics - Your responsibilities as a Christian in business'

That works - if the audience are Christians!

Or 'Economics and ethics - Christian responsibilities in business'

That's probably the best of the lot.

Red Red Robin! Thank you very much!! I really like your last suggestion. As I don't know what the speech is about - I only got the title as part of a conference program - I was not able to give any more context. Thanks again, that was a great help!!