who wrote: "Jeder Koncurrenz fuhrt zum Teufel"?

I could not find the quote.
Two spelling corrections if another researcher wants to try to answer the question:
"Konkurrenz" and "führt" 

till-ga

This is really interesting. The correct spelling of the quote is:
"Jede Konsequenz führt zum Teufel", which translates as "All possible
outcomes lead to the devil". Since 'Konsequenz' has more than one
meaning in German, it could also translate as: "Moralizing always
leads to the devil".

This quotation can be found almost exclusively on Dutch websites,
attributed to Martin Luther, Johann Wolfgang von Goethe, or simply
called a "German proverb". But actually, the saying seems to be
virtually unknown outside Holland. I found very few German sites using
the quote.

Scriptor

"Konkurrenz" means "competition", and a saying "Every competition
leads to the devil" sounds plausible.  But like scriptor, I've only
seen "Jede Kosenquenz" or the Dutch version thereof.