immaculate conception. Do the scriptwriters really not understand what that means?
For that question, you'd have to ask to ask the scriptwriters themselves. I suspect that most of them really don't understand the concept, and those few that do are simply hoping that their audience doesn't. I can't do much about Hollywood, but I will try to clear up the misunderstanding here.
The immaculate conception was a requirement for the virgin birth, but it was an entirely separate event, occurring perhaps fifteen or twenty years earlier.
Christians believe that Mary bore Jesus while still a virgin,
having been impregnated by God's holy spirit without the
presence of any physical father.
This doctrine is properly known as the virgin birth
,
but as you noticed, scriptwriters and other people often refer
to it incorrectly as the immaculate conception
,
which refers to a totally different event,
but which sounds like it might mean the same thing.
It also sounds funnier.
The Roman church teaches the doctrine of original sin
.
When Adam and Eve disobeyed God in the Garden of Eden,
they incurred the death penalty, not only for themselves
but for all mankind.
This sin was passed on to their descendants,
and now each of us inherits it from our parents.
For Jesus's sacrifice to be able to save mankind,
he would have to have been born without sin.
But that raises problems, for just as Mary would have inherited
original sin from her parents,
she would also have passed it on to her son Jesus.
This dilemma is resolved by the knowledge that when Mary herself
was conceived, God caused her to be born without inheriting
the original sin from her own parents.
More technically, Mary was given sanctifying grace
at her conception, something denied to the rest of mankind.
It is Mary's conception without the inheritance of original sin,
a generation before Jesus's,
that is properly known as the immaculate conception
.
The doctrine of original sin is rejected by many Christian denominations, though they do accept the virgin birth doctrine, and both doctrines are rejected by Jews and Muslims. The immaculate conception isn't taught by any denomination other than the Roman church, which itself didn't accept it as dogma until 1854.