A man sees a boy with a box of kittens
The man goes over and says "Oh what cute kittens!"
The boy replies "Yes they are Christian kittens".
About a week later the man sees the boy again with the same batch of kittens.
Once again he walks over and says "my, those are just adorable!"
The boy replies "Yes, they are atheist kittens"
The man asks "wait, weren't they christian before?"
The boy looks at the man and says "Yeah but they have their eyes open now"