Then God said, "Let Us make man in Our image, after Our likeness. And let them have dominion over the fish of the sea and over the birds of the heavens and over the livestock and over all the earth and over every creeping thing that creeps on the earth" (Gen 1:26).In theological circles the concept is called the Imago Dei, Latin for "the Image of God". Humans, according to the beginning of Scripture, are made in the image of God.
What does that mean? Well, some suggest it is a physical similarity. This, of course, makes no sense since God is spirit (John 4:24). But that very well could be one primary component. We have a spirit. The text, on the other hand, suggests at least one component of the image of God in humans. It says, "Let them have dominion." We would, then, be similar to God in the fact that He has given us some measure of dominion. We rule over the earth. An extension to that is found in the following verses where it says, "And God said to them, 'Be fruitful and multiply and fill the earth and subdue it'" (Gen 1:28). There is, then, not only a measure of dominion, but a measure of control. "Subdue it." A task. But included in that command is another similarity to God: "Be fruitful and multiply." We are, then, a reflection of God when we create life. Reproduction is in the image of God. And therein is the primary concept of Imago Dei. We are a reflection of God. Like the moon reflecting the light of the sun, we reflect the glory of God.
One of the key components of the Imago Dei in humans is found indirectly in the simple fact that we are given dominion and we are given commands. Thus, humans, as a reflection of God, are moral creatures. Animals don't share the same moral structures. They don't have rules against theft and murder, for instance, which, when violated, threaten their souls. But as those who reflect the nature of God, we are creatures of morality at the core.
Some have suggested that the Imago Dei is gone. They suggest that it ended when Adam sinned. That concept would suggest that our primary reflection of the image of God was in our sinlessness. When that ended, so did the reflection. This simply isn't true. David, in Psalm 8, repeats the principle. He says, "What is man that You are mindful of him, and the son of man that You care for him? Yet You have made him a little lower than the heavenly beings and crowned him with glory and honor. You have given him dominion over the works of Your hands; You have put all things under his feet" (Psa 8:4-6). Still in effect. When Noah and family left the ark, God instituted human government. In that institution, He called for capital punishment. The notion of putting someone to death for murder, you see, was ordained by God. But the reason for that extreme punishment was given after the Fall. What was the reason? "Whoever sheds the blood of man, by man shall his blood be shed, for God made man in His own image" (Gen 9:6). Thus, the Imago Dei was still in effect after Noah. And the principle was God's baseline for the value of human beings. Animals were not made in the image of God; humans are. Thus, James warns of the faulty use of the tongue: "With it we bless our Lord and Father, and with it we curse people who are made in the likeness of God" (James 3:9). Still in effect.
If you examine the concept in theological circles, you'll find variations in definition and application. That's fine. Suffice it to say that we were created in the image of God and that this fact remains. Being in that image, whatever it means in its entirety, ought to alter how we behave, how we value human life, and how we view our Creator. As a first example, it is the fundamental basis for a pro-life (as opposed to "anti-abortion" or "anti-choice") position. Now, you can work out other applications.