snipAnd defining a fetus, especially at a very early stage (blastocyst?)
as
a human being, is a religious belief, not a fact.

Actually, defining a blastocyst as a fetus is wrong. Human or not. a
Blastocyst is an early metazoan embryo typically having the form of a hollow
fluid-filled rounded cavity bounded by a single layer of cells.

A fetus is defined as an embryo having formed its basic shape.

Actually the religious belief isn't whether it's a human being or not...
it's when does it get a soul. Until that is proven, an impossibility by the
way,this will always be a controversial subject. Even an atheistic
scientist doesn't deny it's human.


snipOne could equally hold the belief (also not a fact) that a fetus only
becomes human when it is capable of surviving outside the womb without
extraordinary measures.
snipThe fact is that there is no scientific definition of the transition
point from embryo to human.

The fact is you are talking gibberish. The medical industry, biologist,
geneticists, etc. all agree on one thing.... it's human. It's a human egg.
It's a human sperm. At conception it becomes a human embryo with all it's
various stages. It then becomes a human fetus with it's various stages and
if the incubation period is successful it becomes a human infant followed by
numerous other human stages of life.