The kingdom as it was, and the kingdom as it is to be, although the same kingdom, is exhibited in the scriptures under Two Covenants, or constitutions. But before adverting more particularly to these it may be necessary to say a word or two in answer to the inquiry, 'What is a Covenant?' It is a word of very frequent occurrence in our scripture, and the representative in our language of the Hebrew berith. In English, covenant signifies 'a mutual agreement of two or more persons to do or forbear some act or thing.' This, however, is not the sense of the word berith when used in relation to the things of the kingdom. Men's compliance or acceptance does not constitute the berith of the kingdom a covenant. It is a covenant whether they consent or not, and is enforced as the imperious enactment of an absolute king. It points out God's chosen, selected, and determined plan or purpose, entirely and independent of any one's consent, either asked or given, and is equivalent to a system of government fixed by the Prince, and imposed on the people without the slightest consultation between them. Accordingly, what is called the covenant in one place, is denominated the law in another. As, 'he hath remembered his covenant for ever, the word which he commanded to a thousand generations; which covenant he made with Abraham and confirmed the same unto Jacob for a law, and to Israel for an everlasting covenant.' 'These are the words of the covenant which the Lord commanded Moses to make with the children of Israel. Thus saith the Lord, cursed be the man that obeyeth not the words of this covenant which I commanded your fathers.' It is evident from this that covenant and law are used as synonymous and convertible terms.
The statements of the New Testament conduct us to the same conclusion. It may be proper to remark here that a berith, or covenant, is expressed in Greek by diatheke. This is the word used in the Septuagint as the translation of berith. It signifies an appointment; not a mutual compact, but the arrangement, settled plan, or institution of one party alone; and it the term used to denote the testamentary deeds of the deceased, in which the will and pleasure of the legatees is never consulted. 'For where a diatheke is, there must also of necessity be the death of the testator; for a testament (diatheke, covenant or will) is of force when men are dead, otherwise it is of no force at all while the testator liveth.
by Dr. John Thomas