"I never said that I support infanticide."
Yes you did. You said that you support abortion.
"Where did your argument about criminal mothers come from?"
If abortion is criminalised, then women murdering their babies is a criminal act.
"your argument about Nazis is completely farfetched"
Is it, though?
"Mere human blood cells are also not real humans, nor are human gametes; they're all just parts of a human being."
Human life begins at the point of conception. If we look for when human life begins, we use scientific criteria that can be found it pretty much any biology textbook. And there is certain criteria that we use for distinguishing between a living entity and a non-living entity. We can look at various characteristics that distinguish humans from every other form of life, but one of the best ways of doing this is through DNA. And at the point of conception, every piece of genetic code that makes you uniquely human and uniquely you is already present. At the point of conception, a new human has formed. Your life began at the point of conception, as did mine, and so did every other human that has ever existed. So human life begins at the point of conception, which means that all foetuses killed by abortion are human. And since the definition of abortion is the deliberate termination of a human pregnancy, and the definition of murder is the killing of one human being by another, abortion is murder, and abortion supporters are responsible for a mass infanticide.