Yes, Google will find it somehow!
They monitor people's browser/search history via Google Accounts/Toolbars/Social Networks and the like - then use that data to augment and prioritize their crawler.
So if a user visits your page while logged into a google account with it's search history tracking enabled Google may find out about your page. You also can't control what users post to social media sites and the like.
You can prevent it's inclusion in google's index though, robots.txt, a simple text file which sits in the www root directory of your server, will stop the GoogleBot in it's tracks.
House your non-google pages in a single directory and exclude like this:-
As @Matteo and @Zaph note this isn't real protection and won't stop determined users finding your content. I use .htpasswd to block areas on my sites in conjunction with Coffee Cup Website Access Manager which outputs hashed htpasswd files and uploads them to your site, and provides multi user management.