Judaism – Religion or Nationality

Hello Rabbi Michael,
I recently heard the opinion (mainly in Zionist – religious circles) that Judaism is not a religion at all but a nation. That is, there is a nation that is the people of Israel and is the focus, and in addition that nation has its own laws, its own culture, its own beliefs, etc., and the identification of Judaism as a religion stems from a mistake.
Do you have an opinion on the subject of whether Judaism is a religion with national characteristics or a nation with its own laws and beliefs? Is there a big difference between these two definitions or do they both mean the same thing in your opinion? And what implications (if any) are there between these two definitions (in relation to secular people, for example)?
Thank you very much.