Why was this command important to God? It’s best to start at the beginning.
Genesis 1:27 declares, “So God created man in his own image, in the image of God he created him; male and female he created them.” We, as humans, were made in the image of God, endowed with dignity and purpose. That purpose is revealed in Genesis 1:28, where God blesses humanity and commands them to “be fruitful and multiply and fill the earth and subdue it, and have dominion over the fish of the sea and over the birds of the heavens and over every living thing that moves on the earth.”
After creating man, God took him to the Garden of Eden to work it and keep it. Yet, for the first time in all of creation, God declared something “not good”: “It is not good that the man should be alone; I will make him a helper fit for him” (Genesis 2:18). So, God created a woman.
Then, Genesis 2:24-25 says, “Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh. And the man and his wife were both naked and were not ashamed.” Here we see the establishment of the marriage covenant. It is a relationship marked by unity, intimacy, and openness before God and each other. So, when sin steps into the picture, we also see disunity, alienation, and shame.
Adultery creates division, redirects intimacy outside of the covenant relationship, and breeds secrecy. It is the violation of the covenant bond God designed from the beginning.