If you’re not sure what the difference is between an atheist, an agnostic and a theist, you might appreciate this explanation from the folks at wordpress.com:
The difference between an atheist, an agnostic and a theist can be summarised by their responses to the question: do you have a dog?
The atheist will simply answer, “No”. If you go to his house to search for a dog, you won’t find one. There will be no signs in the house or the yard that there ever was a dog there. None of his relatives or friends will remember having seen a dog there. They’ll ask, “Does he have a dog? How could I not have known?” And they’ll be absolutely right. There are no signs that there could ever have been a dog at the atheist’s house or indeed anywhere where he spends his time. Not at his home, not at his work, nowhere.
The agnostic who thinks that there’s simply insufficient proof for either having or not having a dog will be a great deal less certain.
When asked, she’ll look around her house searching for traces of a dog. When pressed, she’ll say, “Oh, I’ve searched my house, but what’s to say that there’s not a dog in my garage as I’m searching the house, and what’s to say that dog isn’t going to be in my house while I search the garage?”. If asked, “Do you believe you have a dog, despite there being no signs of it?” She’s likely to answer firmly: “There’s simply not enough evidence to support the fact that I don’t own a dog to come to that conclusion.”
Then there’s the agnostic who doesn’t believe that he owns a dog, but is nevertheless not willing to completely rule out the possibility.
When asked, he’ll say, “I have no dog at home, that’s for sure.” Pondering the question further, he’ll say, “But, obviously, I can never be everywhere all at once. So, there must be some small possibility that there’s a dog out there somewhere that’s got a disk on its collar saying I’m the owner. That I don’t know about it isn’t sufficient proof that it doesn’t exist.”
Needless to say, you won’t find traces of a dog at his home either.
Finally, there’s the theist. When asked, she’ll answer an empathic “Yes!” But if you go to her house and search for a dog, you’ll not find a trace of a dog there either. Nowhere is a dog to be found.
Naturally you’ll ask her why she thinks she has a dog when there’s no evidence. You might find relatives and friends who say she has a dog, but who’ve never seen it, heard it, or felt it licking their face.
“It’s a matter of faith,” the theist will proclaim. “I have faith in this (or that) which says so. My friends say so. My parents said so. So who are you to question the fact that I have a dog?”