“It’s an important moment in the land of Lincoln. We believe in civil rights and we believe in civil unions.” These words punctuated Illinois Governor Quinn’s signature on the Illinois Religious Freedom Protection and Civil Union Act on Monday, January 31.

Illinois becomes the sixth state to legalize civil union or a form of domestic partnership. Five other states protect same-sex marriage. The bill’s sponsor, Rep. Greg Harris, who is openly gay, indicated “there was still more work to do,” referring to passage of a gay marriage bill that he has repeatedly introduced along side of his civil union bill. Most homosexuals consider marriage essential to achieving consummate equality with heterosexuals.

The momentum compels the Christian community to devote itself to defining marriage from a clear biblical and theological perspective. It does not guarantee that such a definition will persuade the government to deter the encroachment upon this sacred ground, but, hopefully, it will offer an intellectual and theological integrity in the debate.

This definition must begin in the creation account. God created both the man and the woman in his image, “So God created man in his own image … male and female he created them” (Gen. 1:27). In this verse, “man” bears the collective sense, which includes both genders, male and female. Thus, God’s image does not appear in the characteristics of one gender alone.

After creating the man, God declared that this creature was incomplete because he was created for mutual relations, “It is not good that the man should be alone” (Gen. 2:18). God fashioned the woman for a correlative union with the man. Genesis 2:24 describes this union, “Therefore a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh.” We call this one-flesh union marriage.

It is significant that God chose to meet man’s relational need with a woman, not another man. The man and woman share a multitude of characteristics in common, but they also bear some very significant dissimilarities, including both physiological and psychological distinctions. Because God created the man and woman for union, the distinctions are complementary and establish an interdependence between the genders. This interdependence is most fully realized in the one-flesh union.

Theologians believe that “one flesh” refers to something more than the sexual union that consummates marriage. Two unique creatures unite together into a single entity, transcending the physical world. This union includes the intellectual, psychological, emotional, spiritual and physical components of the man and the woman. The union involves a process of two whole individuals coalescing into a unity.

Although the one-flesh union transcends the physical, it necessarily includes the union of the male and female bodies. God created each gender with unique bodily features that correspond to the features of the opposite gender. The male and female bodies fit together in natural congruity. When two members of the same gender attempt to unite physically, the union is obviously incongruous and unnatural. Paul uses this description when he describes dishonorable passions in Romans 1:26-27. “For their women exchanged natural relations for those that are contrary to nature, and the men likewise gave up natural relations with women and were consumed with passion for one another, committing shameless acts with men and receiving in themselves the due penalty for their error.”

Paul refers to the bodily union as a part of the one-flesh relationship when he argues against the practice of copulating with prostitutes. Temple prostitution abounded in first-century Corinthian society. Recent converts to Christ in Corinth continued this practice and Paul rebuked them in a letter. He points out, “Or do you not know that he who is joined to a prostitute becomes one body with her? For, as it is written, ‘The two will become one flesh.’” (1 Corinthians 6:16) Sexual intercourse constitutes one component of the one-flesh union, but it does not qualify as marriage because the other two components of Genesis 2:24 are missing, leaving the parents and holding fast to the spouse.

For the discussion of marriage, the bodily union of two people is necessary and that union should follow the natural order. In the created order, marriage is distinguished by a relationship between two people who have committed themselves to the process of becoming one flesh. The unique features of the male and female bodies provide a natural sexual union that is violated when two members of the same gender engage in sexuality.

Governments have the freedom to define marriage any way they choose. One may choose to exclude the sexual union from its definition, while another may choose to limit its definition to the sexual union entirely. They may formulate their definitions using dozens of factors and motives.

But the Church must define marriage from a theological understanding of what the Bible has revealed. Consequently, the Church must require the definition to conform to the created order, the intended purpose of God in his original creation. Anything that compromises this natural order could not be called marriage. The nature of same-sex unions clearly violates this natural, created order.