I'm not sure if you intend "nowaday" as an adverb or an adjective., As an adverb telling when, we'd use "Nowadays." As an adjective telling what kind of people, we'd say something like "modern day people."
"I believe no one" also works.
Of course your last sentence is not a sentence, but it's natural to say. I'd probably use a dash or a colon. I don't know how a guru would put