In “Back to the Future” Doc Brown was incredulous in 1955 when Marty McFly told him that Ronald Reagan was president in 1985. What would be the reaction of 1985 audiences, to be told who would be Chief Executive in 2019?

The short answer is that a belief in reincarnation is not automatically an endorsement of gods (or "devils", whatever they are), and so you can believe in reincarnation and be an atheist too.

As an Atheist, what are your thoughts about the statements: "I don't believe in God" and "I know that God doesn't exist"?

That's an easy one (for me at least): yes, at least the Jesus part.

Which leads us to the modern usage of the term, which has broadened to mean those who do not hold belief in any gods at all.

Can an atheist believe in reincarnation?