I can't speak for humanists/atheists pro-lifers, but from what I read on a few websites -
they see it as violations of human-rights (fetus).
So.....not necessarily religious.
And.....I can see and understand where they're coming from!
We cannot exclude or discriminate on anyone (regardless of race, creed, age or gender or mental/physical capability ) if we're going to uphold human rights.
Otherwise, what we have is a sham!
If the definition of a human being cannot be consistent - then, anyone can be defined as
not human enough at any time, and thus can be subjected to
discriminations of all sorts!
A
human female is biologically designed to carry and give birth to children.
Should we define a woman who see it differently to not be human enough?
Can we say.....she is
"inhuman?"