Why are atheists guaranteed entry into heaven while Christians are only ever sent directly to hell?

No idea why you think that.

A Catholic can be certain of avoiding eternal damnation by completing successfully the Five First Saturdays Devotion in honor of the Immaculate Heart of the Virgin Mary.

They don't. Heaven and hell are imaginary.

You are confused. Do some more research on Christian theology.

::YAWN::

Ps 53:1 "The fool has said in his heart, "There is no God." They are corrupt, and have done abominable iniquity; There is none who does good."

Because the self proclaimed Christian threatened with fire and condemnation, and therefore castigated him/her self.

fumblesmcst00l, you appear to be two sandwidges short of a picnic.

atheists will never goto heaven

Everyone goes to hell when they die (hell is the grave)

We made our own "get out of hell free cards"

We were given free will and we used it.

We made a loop hole and beat god at his own monopoly game.

Sucker isn't playing with a full deck.

Note: no fecal matter was harmed during the writing of this answer.

Atheists DO NOT go to Heaven or Hell. Heaven and Hell DO NOT EXIST.