The Bible never directly forbids abortion. It never outright declares the embryo/fetus a living human. Some say that because God forms us in the womb that it is alive (Isa 44:2; Ps 139:13). God formed the dirt, but it is not alive. Some say that since God knew us before conception it is alive (Jer 1:5). If life existence begins when God knows us, then the Mormons are correct in that we live before conception. Some say that because God ordained our lives before creation, then the unborn is alive (Ps 139:16). Again, knowledge does not denote life unless you are a Mormon. Therefore, these verses do not prove life, but only prove creation, foreknowledge, and providence. In fact, Job 10:19, taken individually, seems to allude that in the womb there is no life, but mere existence.
However, many verses allude that in the womb there is life. John leaped for joy (Luke 1:41), unborn are called "treasure" (Ps 17:14), unborn may have sight (Ps 58:8), hurting the unborn is punishable by death (Ex 21:22-23), and God kills "the precious ones of their womb" (Hos 9:16). Therefore, the Bible seems to hint that there is life in the womb. Science also tells us that eighteen days after conception the unborn has a heartbeat and that it has its own brainwaves at six weeks. At the moment of conception of a healthy child, all the genetic material necessary to become an adult exists. Therefore, it seems that life exists in the womb and that life is an unborn child.
Can we kill the unborn child? Murder is forbidden (Ex 20:13). Killing the unborn child without cause is murder and is, therefore, a sin. What about rape and incest? If your sibling has sex with you or someone sexually assaults you, do you have the right to kill his or her innocent 5-year-old child? No. Nor do you have the right to kill his or her innocent unborn child. What if the health of the mother is at risk? Pregnancy, by definition, is a health risk to the mother and abortion not permitted. These abortions are sinful murder!
God does permit taking life in self defense, so long as the person believes his or her life is in danger (Gen 4:23-24). Therefore, is abortion permitted if the life of the mother is in danger? If the life of the mother is in extreme jeopardy, then taking a life in this case is permitted. Some say that in the Genesis account, Lamech is under attack and that the child is not attacking the mother. Such a conclusion cannot be drawn. Lamech kills two people, and only one is recorded as assaulting him. The other's action and intent are unclear.
In the end, abortion is taking a human life. In all cases, except the life of the mother, abortion is murder. The Holocaust pales in comparison to the abortion rate. It is sin!