Many more milestones of life could be noted here, but the bottom line is, once a human egg is fertilized by sperm, a new human being has come into existence. All information concerning the child's sex, hair color, eye color, and much more is present from the very beginning.
If the newly formed being is not human life, what is it? And how should it be treated?
Some people acknowledge that it may be human life, but say it is not yet a person. They get stuck on terms like zygote or embryo or fetus, but those are just stages of life, like infant or toddler or teenager. What are the signs of personhood?
God, the Author of all life, should have something to say about His creation, and He does! In Psalm 139:13-16, David responds with wonder at how well God knows him:
You created my inmost being;
you knit me together in my mother's womb.
I praise you because I am fearfully and wonderfully made;
your works are wonderful, I know that full well.
My frame was not hidden from you
when I was made in the secret place. . . . your eyes saw my unformed body.
All the days ordained for me were written in your book before one of them came to be.
God's knowledge of us before birth means that we are important to Him even then, because we are made in His image (Genesis 1:26-27). God's Son Jesus was "made in human likeness" (Philippians 2:7), starting out his ministry on Earth as an embryo in the womb of Mary. Then He died on the cross to end our separation from God that was caused by our sin. Romans 5:8 says:
God demonstrates his own love for us in this:
While we were still sinners, Christ died for us.
Because God made us, knows all about us, and loves us, He alone has the right to determine the boundaries of our lives, including the end. From the moment of conception, every human being has worth — is a person — because we bear His image. This is why it is immoral to end the life of another human being, even at its earliest stages. Learn more about what the Bible says about life in the womb.