ANSWER: What the Bible does say about abortion has deeper spiritual consequences than society realizes. Each pregnancy is a miracle from God, made possible so that another human being has the potential of becoming one of his sons or daughters and inheriting eternal life. The real sin of this abominable practice is man's attempt to thwart God's plans for a large family.
Part of the human rationale for supporting abortion is that what is in the womb is NOT a person and that, since it is part of the woman's body, she has the sole right to make decisions about it. The truth is, however, that what is conceived is a new life unto itself. Conception brings together all the genetic instructions needed to create a unique, never-before-existed human being. All that is needed from this point forward is a safe and nurturing environment in which to grow.
What grows within a woman when she becomes pregnant is a human life. According to the Bible, the taking of that life through abortion is murder based on the sixth of the Ten Commandments (Exodus 20:13, Deuteronomy 5:17).
God inspired King David to recognize that his life began at conception when he caused him to write how "wonderfully made" he was in the womb. Notice how many times David attributes to GOD his creation as a human being.
13. For YOU have possessed my reins; YOU have knit me together in my mother's womb. 14. I will praise YOU, for I am awesomely and wonderfully made . . . 15. My substance was not hidden from YOU when I was made in secret and intricately formed . . . YOUR eyes did see my substance, yet being unformed; and in YOUR book all my members were written . . . (Psalm 139:13 - 16, Holy Bible - a Faithful Version throughout)
The Bible does speak of knowing a person even before they are created in a female (see Jeremiah 1:5, Luke 1:13 - 17, 31 - 33). It even records a human growing in one womb responding to the presence of another one Who had just begun their journey of growth.
39. And Mary rose up in those days and went with haste into the hill country . . . 40. And entered the house of Zacharias and greeted Elizabeth. 41. Now it came to pass that when Elizabeth heard Mary's greeting, the babe (John the Baptist) leaped in her womb . . . 44. For behold, as soon as the sound of your (Mary's) greeting reached my ears, the babe in my womb leaped in exultation (Luke 1:39 - 41, 44)
Note that right after God miraculously caused the conception of Jesus in Mary's womb she travelled "with haste" to stay with Elizabeth for three months (verse 56). Mary could not have been more than a few weeks pregnant with Christ when she spoke to Elizabeth. These verses tell us that a six-month old fetus not only detected the presence of a person who had been conceived just WEEKS earlier but also recognized their mother's voice AND responded accordingly! It would be ridiculous to think that Elizabeth's child was responding to just a few weeks old "mass of tissue" in Mary that was not yet the Son of God!
Abortion has been sadly practiced and justified by humans for a very long time. In fact, according to Roman law, even a newborn baby was legally not considered a person until the father accepted him or her as a family member (The IVP Bible Background Commentary, comments on 1Corinthians 7:1 - 7). Although taking the life of someone in the womb was widely practiced in antiquity, it was unanimously condemned by both Christians and Jews.
Abortion, simply put, is man's deceived attempt to deny God a family through murder. Clearly, such behavior is not his perfect will.
What grows inside a pregnant woman is a child, someone with a purpose in his great plan for all man. One has to wonder what things in the world could have been different if killing unborn babies was not an option, if millions of innocent humans were not killed while they grew in the womb.
Based on what the Bible says, human life begins at the moment of conception. It begins the moment sperm and egg unites and brings together all the genetic instructions necessary to produce a unique human. Killing what God has formed, through abortion, is a sin.