If you then claim that an unfertilized egg cell isn't a human but a fertilized egg cell is, the only different between the two is that it has gone from 23 single chromosomes to 23 pairs of chromosomes. If that is your criteria, then that means a skin cell is also a human.
Can a sperm or egg differentiate into a human being? No. A zygote is the only thing that can differentiate into a human being. And if you are pro-abortion, again, that means there is no difference between a zygote, embryo, and fetus.
Let's make it simple - is a fetus human life? What separates a fetus at 8.5 months of a development and a baby that is post birth by 1 day? What makes it okay to end the life at 8.5 months, but not post birth by 1 day.
Being born is not the difference, the life inside the womb and outside the womb is the same. At 8.5 months, almost all development has been completed. So it would be the pro-abortionists with arbitrary limits as to what they constitute as human life.
Abortion becomes more unethical as the baby is further developed in the womb. I don't care if a zygote is aborted. It just becomes more cruel as you go on.
That's just not true. They can sense their environment, they can react to stimulus such as bright lights, pain, or skin to skin contact, they can communicate that they are hungry or tired, etc. A fetus before the limit of viability cannot do any of that because it does not have a functioning cerebrum.
So your limit for abortion would be the ability to respond to stimuli, then?
A plant can respond to stimuli, so can insects. That does not mean they are "conscious". Babies are not aware of what's going going on, they are essentially floating balls of cells merely existing. I consider consciousness to be a condition at which you are aware of what is going on, and surely babies that are 1 or 2 days do not possess any ability to recognize or understand their environment at any deep level. By baby, I mean one that is under 1 week old. When you are an infant, your brain develops rapidly.
I've already addressed this. Being temporarily unconscious is not the same as having no capacity for consciousness because your brain has either died or doesn't exist.
Exactly, this is my point, similarly, a zygote, embryo, and fetus have the capability for consciousness, which is why it is a tragedy to abort them.