>Is their any kind of security threat if I make all of my logins as >authors?
Yikes! This is my first time installing a blog, but it sounds like a bad idea to me.
The blog I set up is already inside a password-protected folder, for members of a choir I belong to. I installed it so all the members of the marketing committee could post drafts of publicity material, and comment on them. But I'd never do that with a publicly-accessible blog.
I'm assuming you're the administrator of your blog. You can choose to be the only one you allow to make posts, by making all registered users subscribers by default. That means they can only comment, or, if you turn off comments, they can only read. If you know someone you'd like to give posting privileges on your blog to (ie, that you trust not to be a nimrod on your site), you can have them register as a user, then go into "Users" and raise their status to author, while leaving everybody else as a subscriber. Conversely, if they disappoint you, you can always revoke their authorship privilege. And it is a privilege; you're the blog owner, so you're the boss.
I think most people starting out with a public blog make themselves admins, and all other registered users subscribers. Letting Joe Q. Public register and start posting on your public blog would attract all kinds of spam.