You say “…you attempted to make claim that there is only a religious argument for any stage of human life to be a human”. Actually not so. I make the claim that there is only religious argument to claim that the single cell resulting from a just-fertilized human egg is a fully human being with all civil rights intrinsic as a human being, not any stage of human life.
There are many non-religious conditions that could be considered sufficient for a life to be fully human, and thereby to enlist the power of the state at that point. Roe v. Wade made such a condition when it ruled on viability outside the womb. Acquinas did likewise with the condition of “quickening”. Non-religious arguments could be marshaled behind either of those conditions, or others, to justify enlisting civil law at that point.
I do not claim the just-fertilized egg is not “alive”, but that it is only alive in the same sense that all living cells are alive. Being alive in that sense is entirely distinct from being a full human being with all the rights intrinsic to that condition. You are certainly free to believe that the single cell is a full human being, but you aren’t going to convince anyone else with the arguments “because I say so” or “because I so strongly believe it’s true”.
As to whether science “proves [my] assertion as wrong” and thereby supports the “on conception” argument, here are the defined conditions upon which science determines life: The current definition is that organisms maintain homeostasis, are composed of one or more cells, undergo metabolism, can grow, adapt to their environment, respond to stimuli, and reproduce. Any bacteria cell qualifies as alive by science. This is what I mean when I say the Zygote is alive in the same sense as any bacteria cell. This is far as science goes regarding life. Science merely proves that a human zygote is alive in a cellular sense, and that its DNA is human; science does not prove that the zygote is fully human in the sense of possessing all the intrinsic rights of a human being; that question is a matter of philosophy and religion. And that is the question on which civil law must rest.
You may well characterize a sheep or a human derived from a stem cell rather than an egg cell to be “a Frankenstein monster…unnatural, not normal.” But you can’t make a convincing argument that the result, indistinguishable from any adult by the “natural, normal” derivation, is not alive. Ethics rightly, in my opinion, prevents cloning humans, but the scientific certainty that it can be done proves that every stem cell has the potential. Therefore this presents an argument that the human egg cell is not an absolute requirement for a living human being to be truly human. There must be other requirements for full humanity, and the “on-conception” proponents haven’t yet wrestled with what those might be; they are missing in action in the debate on other criteria.
Instead of participating in that debate, the On-Conception people simply say “Here is my conviction; prove me wrong to my satisfaction or I win”. It’s no wonder we are getting nowhere.
To claim full human status of the fetus at some specific point between conception and birth — and remember what we are talking about here isn’t your convictions on the subject but your demand that the power of state be enlisted to criminalize any action that kills the fetus after the time you designate — one must make a convincing argument that certain named conditions for full humanity are met at that point in time.
It’s time to debate what those conditions might be.