Private Pages Redirect to 404

Every page on my blog is set to private creating somewhat of a logged in user only site.. why does the homepage redirect to the 404? I would like it to redirect to a page that shows the look of the site so people can get a feel but not allow them to see content.

I’m trying to accomplish this with code and not a plugin but I guess I’ll have to use one if I can’t.

Thanks in advance!