Well, since I consider the concepts of comic book superheroes and religious deities to be equally improbable the questions are, shall we say, rhetorical.
If we define a unicorn in the usual way, four legs, tail, mane, horn, etc, you can think about it, know what it is, and decide whether there is such a thing.
But if you add another property, "existence", then things get more interesting. A unicorn is something that exists, has four legs, tail, mane, horn, etc. Does it exist? Yes, of course, by definition!
Re: gotta give up one or more attributes of God if you don't what an evil God
It all goes to show the scriptures weren't written by philosophers or logicians or scientists, they were written by people who just liked a good story.
“An artist is someone who can hold two opposing viewpoints and still remain fully functional.”