How does God define marriage?

And Adam called his wife's name Eve; because she was the mother of all living. (Genesis 3:20, Holy Bible, KJV)

Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband. (1 Corinthians 7:2, Holy Bible, KJV)

Nevertheless neither is the man without the woman, neither the woman without the man, in the Lord. (1 Corinthians 11:11, Holy Bible, KJV)

Behold, their husbands love their wives, and their wives love their husbands; and their husbands and their wives love their children. (Jacob 3:7, Book of Mormon)

Wherefore, my brethren, hear me, and hearken to the word of the Lord: For there shall not any man among you have save it be one wife. (Jacob 2:27, Book of Mormon)

And again, verily I say unto you, that whoso forbiddeth to marry is not ordained of God, for marriage is ordained of God unto man. (Doctrine and Covenants 49:15)

We, the First Presidency and the Council of the Twelve Apostles of The Church of Jesus Christ of Latter-day Saints, solemnly proclaim that marriage between a man and a woman is ordained of God and that the family is central to the Creator’s plan for the eternal destiny of His children...The family is ordained of God. Marriage between man and woman is essential to His eternal plan. Children are entitled to birth within the bonds of matrimony, and to be reared by a father and a mother who honor marital vows with complete fidelity. (The Family a Proclamation to the World)

Many in the world are confused about the concept of marriage. Some claim it to be no more than a civil institution - a concoction of man. Others claim it to be a flexible concept, amenable to change as society's views evolve. And still others are firm in their belief that marriage is a sacred union between one man and one woman - an institution appointed by God; a concept not subject to alteration.

Many appeal to the Bible as they make their claims. Some use scripture to support the current "definition" of marriage. Others use it to refute. No matter the stance, it is clear that the question will not be settled by an appeal to the Bible alone. The variance in interpretation of that body of scripture is too vast. Reference solely to the Bible on this point is as precarious and futile as is a door with only one hinge. Even the Bible itself is clear about it's utility in solidarity: "In the mouth of two or three witnesses shall every word be established" (Matthew 18:16).

The plain and precious doctrines contained in the Book of Mormon serve as a second hinge upon which the door of truth is hung.

Moreover, the clarity and precision of modern-day revelation and scripture leave no question as to the concept and definition of marriage.

Taken together, the Bible, the Book of Mormon, and modern-day revelation through prophets of God boldly and perfectly answer every question regarding marriage. God's definition of marriage is immutable, even as He is. It was the same in the days of Adam and Eve as it is in our day. Those who wish to redefine marriage according to a "new morality" do not understand, or simply refuse to believe, that marriage is a divine institution, ordained by God to form the foundation of eternal families.

Does the Bible contain all of God's words to man?

And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus. And all scripture given by inspiration of God is profitable for doctrine, for reproof, for correction, for instruction in righteousness: That the man of God may be perfect, thoroughly furnished unto all good works (from the Bible, 2 Timothy 3:15-17).

Know ye not that there are more nations than one? Know ye not that I, the Lord your God, have created all men, and that I remember those who are upon the isles of the sea; and that I rule in the heavens above and in the earth beneath; and I bring forth my word unto the children of men, yea, even upon all the nations of the earth?

Wherefore murmur ye, because that ye shall receive more of my word? Know ye not that the testimony of two nations is a witness unto you that I am God, that I remember one nation like unto another? Wherefore, I speak the same words unto one nation like unto another. And when the two nations shall run together the testimony of the two nations shall run together also.

And I do this that I may prove unto many that I am the same yesterday, today, and forever; and that I speak forth my words according to mine own pleasure. And because that I have spoken one word ye need not suppose that I cannot speak another; for my work is not yet finished; neither shall it be until the end of man, neither from that time henceforth and forever.

Wherefore, because that ye have a Bible ye need not suppose that it contains all my words; neither need ye suppose that I have not caused more to be written.

For I command all men, both in the east and in the west, and in the north, and in the south, and in the islands of the sea, that they shall write the words which I speak unto them; for out of the books which shall be written I will judge the world, every man according to their works, according to that which is written (from the Book of Mormon, 2 Nephi 29:7-11).

The Bible is not the only depository of God's words to man. Nowhere in the Bible does it say that God will cease speaking to man or that he will close His canon of scripture. Many will try to argue that St. John the Divine "closed the canon" of revelation from God when he warned: "If any man shall add unto these things, God shall add unto him the plagues that are written in this book" (Revelation 22:18). A simple, basic (and too often lacking) understanding of how the Bible came about makes clear that John was not referring to the Bible as we know it today when he warned against adding to or taking away from "this book." One writer recently explained: "There is now overwhelming consensus among virtually all biblical scholars that this verse applies only to the book of Revelation, not the whole Bible. Those scholars of our day acknowledge a number of New Testament 'books' that were almost certainly written after John’s revelation on the Isle of Patmos was received. Included in this category are at least the books of Jude, the three Epistles of John, and probably the entire Gospel of John itself" (see Ensign magazine, May 2008, 91-94). Even more dramatically, Moses did not close the canon of scripture when he told the Israelites in the wilderness: "Ye shall not add unto the word which I command you, neither shall you diminish ought from it" (Deuteronomy 4:2). If the same logic so commonly applied to John's words in the Book of Revelation were applied to Moses' words in Deuteronomy, so-called "mainstream Christianity" would have to reject over 90% of the current Bible. This, of course, would be foolish--but no more foolish than rejecting all of the inspired scripture that has been recorded since John completed his books.

Scholarly logic and common sense aside, the veritable fact that God continues to speak to man is evidence of His love for all men, women, and children, no matter the time or place of their existence on this earth. The Bible is tangible evidence that God spoke to man in one part of the world. The Book of Mormon is tangible evidence that God spoke to man in another part of the world at nearly the same time. It testifies plainly and boldly that He will never cease speaking to man. Other scriptures that have been compiled since the completion of the record from which the Book of Mormon was translated provide tangible evidence of this bold assertion of constant communication from God to man even into our day (see scriptures.lds.org).

I have read the Bible and have felt of its divine power. I know that it is truly the word of God. I have also read the Book of Mormon and have felt the very same power testify that it, too, is the word of God. Recognizing this fact has helped me understand that "continuing revelation does not demean or discredit existing revelation. The Old Testament does not lose its value in our eyes when we are introduced to the New Testament, and the New Testament is only enhanced when we read the Book of Mormon" (seeEnsign magazine, May 2008, 91-94).