Now, if nostr:nprofile1qqsr836yylem9deatcu08ekfj8qj9f2aypq8ydt0w8dyng8zp8akjsqpr9mhxue69uhhyetvv9ujuur0wd6x2u3wwpkxzcm99uz2gxag is meaning that those who profess to be Jewish, but do not have faith in their Messiah, are unbelievers, I would definitely agree with that.

But no, I would not claim Jesus isn't Jewish. He is the promised Messiah, the suffering servant, the son of David and Son of God who will sit on David's throne forevermore. Cannot get much more Jewish than that.