Two people reproduced 7 billion people.

[Aegrus]

They didn't just give birth to everybody on Earth today. It's called reproduction. I believe you've heard of it? Two gives birth, their children give birth, their children's children give birth, their children's children's children gave birth, etc. etc. Years and years.

How is this a fallacy? I understand some atheists' points, but this one is ridiculous.

The implied issue is genetics and inbreeding. Most Christians argue that Adam and Eve had perfect genetics, and thus there wouldn't have been harmful mutations.

Atheists typically ask for proof of this claim, or for proof that either person actually existed. There never is any, but the religious answer is always "faith."

End result; nothing changes. Religious are still religious, atheists are still atheists.