The Bible’s answer
Our Creator established rules governing marriage long before governments began regulating the institution. The opening book of the Bible tells us: “A man will leave his father and his mother and he must stick to his wife and they must become one flesh.” (Genesis 2:24) The Hebrew word “wife,” according to Vine’s Expository Dictionary of Biblical Words, “connotes one who is a female human being.” Jesus confirmed that those yoked together in marriage should be “male and female.”—Matthew 19:4.
Thus, God intended marriage to be a permanent, intimate bond between a man and a woman. Men and women are designed to complement each other so they may be capable of satisfying each other’s emotional and sexual needs and of providing children.