If there are those quick to discount and refuse Christianity and other religions derived from ancient writings, why is it allowed to believe in reincarnation which is also derived from ancient writings.

What is it that makes one true and the other not true?

Is it because reincarnation is the easy path and requires no effort on your part?

Are we that lazy and stupid so we place a higher value in our earth-bound finite state than the true reality of infinite state?

We are encased by, and composed of, infinite kinetics, structures, and mind (Math for example). That's a given and not from any ancient writings. It's current and present.

Why pick one over the other if all come from ancient writings? We all love a good fiction or Sy-Fy story. You don't think people of the past didn't either? You don't consider some of these writings aren't more than a fun story to tell?

Just because something comes from the past doesn't make it an absolute, a fact, or a truth anymore than doom or riches predictions for the future.