What is the sanctity of life? Why do Christians believe in the sanctity of life?

from the old testament

• 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). God literally breathed life into man, something He did not do with other life forms (Genesis 2:7). We bear God's image (Genesis 9:6). Anything that harms or mars a human life mars the reflection of God Himself. Christians must approach human life with a sense of reverence for the Creator who is reflected in each person’s life.
• Another reason we have reverence for human life is because all human life is owned by God. In Exodus 19:5 God declares that "all earth is mine.” By extension, every human life on the earth belongs to Him as well.
• In Leviticus 24:21 God instructs 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. The penalty for killing an animal was to pay a monetary fine, but the penalty for killing another person required one’s own life (cf. Genesis 9:5–6).
• The psalmist says when life begins in Psalm 139:13: "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.
• 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. As such, each life matters and is precious in His sight.
• In Jeremiah 1:5, God tells the prophet Jeremiah, "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." God began forming Jeremiah in his mother's womb. Likewise, God forms the rest of us while our mothers are in pregnancy.

from the new testament

• In John 13:34–35 Jesus told 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.” We should extend love to everyone, including humans in the womb, those who are developmentally handicapped, and those who are very old.
• 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." Our bodies (as well as others’ bodies) are not our own to hurt or destroy.

implications for today

Sanctity means the quality of being holy, sacred, or set apart. God values human life above other life forms, and 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." 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; Deuteronomy 10:18–19; Ezekiel 45:9). 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.