I am sure most people have heard this one...
Two twin fetuses are talking inside their mother's womb.
A: Do you believe in life after birth?
B: Of course I do. It is obvious that there is life after birth. The purpose of our stay in here is to become strong enough and be prepared for real life.
A: Nonsense! There can be no life after birth. Can you imagine what kind of life that would be?
B: Well, I am not aware of the details, but I believe there will be light and we will be walking with our own legs and eat with our own mouths.
A: Nonsense! It is impossible to walk with your own legs and eat with your own mouth! This is ridiculous! We have an umbilical cord for that. We feed through it. Here is what I can tell you: there cannot be any life after birth, because our true life - the umbilical cord, is too short anyway.
B: Even so, I am sure life after birth is totally possible! Just... everything will be different from now. Just imagine!
A: But no-one has ever come back from there! Life just ends with birth! In other words, life is nothing but suffering in the darkness.
B: Oh, no! Don't say that... I am not sure what life after birth looks like, but I believe we will meet our Mommy and she will take care of us.
A: Mommy!? So you really believe in the existence of Mommy? And where do you think She is? How does She look like?
B: She... She is everywhere around us, we reside in Her, we are only able to live and move thanks to Her; without Her, we cannot exist.
A: Bullshit! I have never seen any Mommies, therefore it is more than clear that She does not exist.