Sanctity means the quality of being holy, sacred, or set apart. Believing in the sanctity of life means believing that human life is somehow holy, set apart, or different from other life forms. The question is "Why do Christians believe that human life is set apart?"
What is the sanctity of life? Why do Christians believe in the sanctity of life?
First, Christians believe human life is sacred because humankind is the only life form to have been created in God's image, after His likeness, and God is holy (Genesis 1:27). We are also told that God literally breathed life into man, something He did not do with other life forms (Genesis 2:7). Something in the way God created humans reflects His attributes. In other words, we bear God's image. So anything that harms or mars a human life also therefore mars that reflection of God Himself. Therefore Christians approach human life with a sense of reverence for the Creator who is reflected in that life.
Another reason Christians have reverence for human life is because we believe all human life is owned by God. In Exodus 19:5 God declares that "all earth is mine" and by extension, every human life on the earth belongs to Him as well. First Corinthians 6:19–20 goes so far as to say, of believers, "…You are not your own, for you were bought with a price. So glorify God in your body." Deuteronomy 32:39 teaches that God not only owns each life, but that He is responsible for the life and death of each person as well. It says, "'See now that I, even I, am he, and there is no god beside me; I kill and I make alive; I wound and I heal; and there is none that can deliver out of my hand." Psalm 139:16 shows that the days of each person's life were written in God's book before any of them came to be. Christians believe that human lives belong to God and only He is in charge of the giving and taking of that life.
It seems possible that because God is the holy, eternal creator and human life is only temporary and marred by a sinful nature, that God may not place a very high value on human life. However, the Bible teaches the opposite. In Leviticus 24:21 God instructed the nation of Israel that "Whoever kills an animal shall make it good, and whoever kills a person shall be put to death." The Hebrew word for "shall make it good" is shalam which means to repay, recompense, or make restitution. So essentially the penalty for killing an animal is to pay a monetary fine, but the penalty for killing another person is much steeper, to pay with one's own life. Here God sets the standard as to how human life and animal life are valued differently. In the following verse, God states the reason for that difference, and it has to do with who He is. "You shall have the same rule for the sojourner and for the native, for I am the LORD your God" (Leviticus 24:22). His being "the LORD your God" is the reason human life has value beyond other life forms. It's also interesting to note that this value in human life is not just to be a rule for the Jews, but that "you shall have the same rule for the sojourner and for the native." Every human life is valued by God.
The next question becomes, "When does human life begin?" In Jeremiah 1:5, God tells the prophet, "Before I formed you in the womb I knew you, and before you were born I consecrated you; I appointed you a prophet to the nations." Here we see God forming Jeremiah in his mother's womb. The Psalmist echoes this sentiment in Psalm 139:13 saying, "For you formed my inward parts; you knitted me together in my mother's womb." The Bible teaches that God is intimately involved in forming human life and that it happens in a mother's womb well before birth, which is why most Christians do not condone abortion.
Christians believe that human life reflects the image of our holy God, that God owns the right to give and take away life, that God values human life above other life forms, and that He is intimately involved in forming each life within the womb. These truths point to the fact that people matter to God. He commands mankind to value people the same way He does. Jesus quotes Leviticus 19:18 in Matthew 22:39 as the second greatest commandment: "You shall love your neighbor as yourself." He also tells His disciples, "A new commandment I give to you, that you love one another: just as I have loved you, you also are to love one another. By this all people will know that you are my disciples, if you have love for one another" (John 13:34–35).
The Bible is filled with practical ways we're to value human life by loving others: tending to the sick, visiting the imprisoned, feeding the hungry, clothing the needy, seeking justice for the oppressed, and caring for orphans, widows, and strangers (Matthew 25:35–36; James 1:27; 1 John 3:16–18; Ezekiel 45:9; Deuteronomy 10:18–19). We should be agents of love and compassion in the world, alleviating suffering wherever we can and remembering that each human life bears the image of our God. Ultimately, we should be sharing the gospel "not wishing that any should perish, but that all should reach repentance" because that's how much God values human life and He desires that we do too (2 Peter 3:9).
What does it mean to be fearfully and wonderfully made (Psalm 139:14)?
Does life begin at conception according to the Bible?
Abortion - What does the Bible have to say?
Does the Bible say anything about euthanasia?
Why did God create humanity?
Truth about Humanity