In the creation story Genesis 2:18-20 we see that "God formed out of the ground various wild animals and various birds of the air" and brought them to the man, because it was "not good for the man to be alone." But "none proved to be a suitable partner for the man."
So God formed a woman from the side of the man’s body. God created the woman and man to live side by side, not above or beneath each other, or behind or in front of each other, but side by side. They were created to be equal partners. They were given a unique relationship shared by no other creatures — to be suitable partners in the sacred bond of marriage.
When God brings the woman to the man (Genesis 2:23), the man says: "This one, at last, is bone of my bones and flesh of my flesh."The woman and man are formed of one being — united as one — with each other.
The story concludes (Genesis 2:24): "That is why a man leaves his father and mother and clings to his wife, and the two of them become one body."
A married couple forms one body, one flesh, one sacred union in their relationship. Their marital unity is willed and ordained by God.
Because a married couple becomes one body, the intimacy of our lovemaking is a sacred act — serving a holy purpose — in our marriage sacrament. In our lovemaking, we embody the unity God has called us to live out in Christian marriage. The intimacy we share becomes a sign of the intimate love shared between Christ and his church.
As our intimacy generates an enduring, unbreakable bond, we give the world a glimpse of the deep, faithful, constant and passionate love Christ shares with the people of God.