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In the books, articles, videos, and audio teachings of Spirit & Truth Fellowship we call the administration in which we live “the Administration of the Sacred Secret,” and we translate the Greek word musterion as “Sacred Secret.”  We believe that “Sacred Secret” is the best translation of the Greek word musterion, a Greek word that most Bible versions translate as “mystery.” For years we have translated musterion as “secret,” but noticed that in Rotherham’s Emphasized Bible, Joseph B. Rotherham, who was a biblical scholar of the first rank, translated musterion as “sacred secret.” We studied the subject and have come to agree with Rotherham, and our reasoning for using “sacred secret” as the translation of the Greek word musterion is presented below.
Although many Bible versions render the Greek word musterion as “mystery,” that is not a good translation. In fact, “mystery” is a transliteration of the word musterion, not a translation of it. “Transliteration” is when the letters of a word in one language are brought across into another language. The prefix “trans” means “across,” and the Latin littera means “letter.” Thus, transliteration is literally “bringing across the letters.” In contrast, “translation” is bringing the meaning of a word in one language across into another language. If we are going to have the meaning of the Greek brought into English, we must translate, not transliterate.
The English word “mystery” means something that is incomprehensible, beyond understanding, unknowable. Thus it is common in religious circles to speak of things such as the “Trinity” as “mysteries” because they cannot be understood. In contrast, a “secret” is something that is known by someone but unknown by others. A surprise birthday party is a “secret” to the person having the birthday, but known by those who will attend it. The Greek word musterion does not mean “mystery,” it means “sacred secret,” that is, a secret in the sacred or spiritual realm that must be made known by God. That musterion refers to a secret, and not to our standard meaning of “mystery,” is well documented by Greek scholars, and because this point is vital to the thesis of this article, we will cite a number of sources.
Musterion: In the NT it denotes, not the mysterious (as with the Eng. Word), but that which, being outside the range of unassisted natural apprehension, can be made known only by divine revelation, and is made known in a manner and at a time appointed by God. 
But whereas “mystery” may mean, and in contemporary usage often does mean, a secret for which no answer can be found, this is not the connotation of the term mysterion in classical and biblical Gk. In the NT, mysterion signifies a secret which is being, or even has been, revealed, which is also divine in scope, and needs to be made known by God to men through his Spirit. 
But while the musterion thus implies something hidden, and inaccessible to the unaided reason, and usually also of weighty import, it by no means necessarily denotes anything strictly mysterious and incomprehensible. The fact or truth, though requiring to be revealed, may, when revealed, be of a very elementary character. 
Mystery in the NT does not deal with the unknowable, but with what is imparted by revelation. 
The mystery of the New Testament has been described as an ‘open secret’; matters previously kept secret in God’s eternal purposes have now been or are being revealed (Eph. 3:3-5; 1 Cor. 2:7-8). 
Numerous other sources give the same information, and the point is that the word musterion does not mean “mystery,” and should not be translated that way. Although God kept His Sacred Secret a secret for years, it has now been made known.  There are a number of verses showing that a musterion can be revealed by God and understood by mankind. Because it is important to understand this point, I will quote quite a few of them.
Matthew 13:11b (KJV)
…it is given unto you to know the mysteries [musterion] of the kingdom of heaven…. 
1 Corinthians 2:7, 8a and 10a, (KJV)
(7) But we speak the wisdom of God in a mystery [musterion], even the hidden wisdom, which God ordained before the world unto our glory:
(8a) Which none of the princes of this world knew….
(10a) But God hath revealed them unto us by his Spirit….
Romans 16:25b and 26a
(25b) …the mystery [musterion] hidden for long ages past,
(26a) but now revealed and made known through the prophetic writings by the command of the eternal God….
And he made known to us the mystery [musterion] of his will according to his good pleasure, which he purposed in Christ,
the mystery [musterion] that has been kept hidden for ages and generations, but is now disclosed to the saints.
Now that we have established that musterion does not mean “mystery,” and that a musterion can be revealed and understood, we will show why we translate it as “sacred secret” and not just “secret.” The Greek language uses musterion for secrets in the religious sphere, but has another word, kruptos, for secrets that are in the secular realm.  The word kruptos appears in many places in the New Testament. For example, Jesus said to give alms in secret (Matt. 6:4-KJV); he taught that every secret thing will be brought to light (Mark 4:22-KJV); he went to Jerusalem in secret (John 7:10-KJV); God will judge men’s secrets (Rom. 2:16); and, prophecy reveals the secrets of the heart (1 Cor. 14:24 and 25).
The verb krupto also appears many times in the New Testament. Examples include: a city on a hill cannot be hidden (Matt. 5:14); the wicked servant hid his talent in the ground (Matt. 25:25); a Christian’s new life is hidden with Christ in God (Col. 3:3); and, Moses’ parents hid him after he was born (Heb. 11:23).
From the above information we see that translating musterion as “secret,” which some versions do in some places, does not bring out the true meaning of the Greek text. Anyone reading the Greek New Testament immediately understands whether God is speaking of a secular secret (kruptos) or a sacred secret (musterion), and a good translation brings out that difference. When a version translates both words as “secret,” the truth that God so clearly communicated in the Greek text is lost. When translators use “secret” for kruptos and “mystery” for musterion, the words are not confused, but the English Bible is made to say something that it just does not say—that the things of God are mysterious. 
Is there a way to translate kruptos and musterion such that the meaning of the Greek words is communicated clearly into English? Yes, there is. There is not one time in the New Testament where musterion cannot be fittingly translated as “sacred secret.”  If we translate kruptos as “secret,” and musterion as “sacred secret,” the meaning of the Greek is communicated clearly, and we English-speaking people are in a better position to know and understand what God has said in His Word.
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