Human reproduction serves to create new human beings and with these human beings comes a soul. The soul appears with the person at the moment of conception, making him a complete human being from the very start. This is why abortion is considered murder: the abortionist has rent the soul from a living human body, the soul being the source of a full life for human beings. If there was no soul present in the human at the time of conception and it entered the body at some later stage, then until that moment the fetus would hypothetically be nothing more than an animated body, similar to how animals and plants are alive but without souls. Thus, if this were the case, abortion would not be murder, but rather a termination of a non-human entity, at least until the soul finally joined the body. However, there is no evidence that the soul can enter the body at any time later than conception. Since the soul is intrinsic to human beings, it absolutely must be present at conception and therefore abortion is murder.