The word commonly translated "covenant" in the Hebrew Old Testament is the word "berith." Berkhof notes that most argue that it comes from the Hebrew verb "barah", which means "to cut." Such an etymology, he points out, is commonly understood as referring to the covenant ratification of Gen. 15:17. Others, he notes, thinks it comes from the Assyrian word "beritu", for "to bind." Such an etymology of the word would suggest that it means "to bind." He notes the importance of the question of etymology when he argues that if the word means "berith", then the word refers to a "mutual voluntary agreement", which he terms "dipleuric", though he also insists on the sovereign administration of the covenant when he argues that biblically, the word must also be "monopleuric" insofar as it refers to an arrangement which is sovereignly imposed on a party subordinate to the one enacting the covenant. He argues that "berith" is synonymous with "choq" or "appointed statute or ordinance"(Ex. 34:10; Isa. 59:21; Jer. 31:36; 33:20; 34:13) if it is understood more in terms of a sovereign disposition imposed on another:
Hence we also find that karath berith (to cut a covenant) is construed not only with the prepositions ’am and ben (with), but also with lamedh (to), Jos. 9:6; Isa. 55:3; 61:8; Jer. 32:40. Naturally, when God establishes a covenant with man, this monopleuric character is very much in evidence, for God and man are not equal parties. God is the Sovereign who imposes His ordinances upon His creatures(Berkhof, Systematic Theology).
Of particular importance for Berkhof's understanding of the "covenant" as a sovereign administration is its translation as "diatheke" in the Septuagint. Indeed, he notes that the Hebrew "berith" is always translated in such a manner except for Deut. 9:15, where it is translated "marturion", meaning "witness", and 1 Kings 11:11, where it is translated "entole", meaning "commandment." What he notes is how unusual this is on the grounds that "diatheke", properly speaking, does not mean "covenant" as something that is a mutual contract, but rather, a disposition or a testament. "Suntheke" is the usual word for covenant, he points out, and this term is used interchangeably with "diatheke" in the LXX rendering of Isa. 28:15. The question he is preoccupied with why "diatheke" is substituted for the more usual term for covenant, "suntheke." He concludes that the most probable reason for this is that "suntheke" typically communicates a degree of equality of parties that is incompatible with the more scriptural idea of a sovereign disposition or administration, so far as God's relationship to man is concerned.
The idea that the priority belongs to God in the establishment of the covenant, and that He sovereignly imposes His covenant on man was absent from the usual Greek word. Hence the substitution of the word in which this was very prominent. The word diatheke thus, like many other words, received a new meaning, when it became the vehicle of divine thought, This change is important in connection with the New Testament use of the word(Berkhof, Systematic Theology)
He then raises the controversy surrounding the translation of the word, particularly in Heb. 9:16, 17. Should it be understood as meaning "covenant" or "disposition/testament"? Some follow Berkhof's emphasis on the disposition/testament idea concerning its use in the NT in general, whereas others argue that the idea of a mutual contract is in mind throughout most of the New Testament. Berkhof actually agrees with the latter, rather than choosing to emphasize the disposition/testament notion. He concludes that the reason "diatheke" is so often used is in more to emphasize the priority of God in administering the covenant rather than using another word and risking importing the notion of equality of parties into the covenant idea.
But what is a 'covenant'? Berkhof notes that the concept preexisted its use in the Bible. It would be important, however, to not commit the genetic fallacy and suppose that the biblical writers merely borrowed the concept from surrounding notions in such a way that the genesis of the Jewish and Christian religions can be reduced to merely accidental and historical cultural developments:
The covenant idea developed in history before God made any formal use of the concept in the revelation of redemption. Covenants among men had been made long before God established His covenant with Noah and with Abraham, and this prepared men to understand the significance of a covenant in a world divided by sin, and helped them to understand the divine revelation, when it presented man’s relation to God as a covenant relation. This does not mean, however, that the covenant idea originated with man and was then borrowed by God as an appropriate form for the description of the mutual relationship between Himself and man. Quite the opposite is true; the archetype of all covenant life is found in the trinitarian being of God, and what is seen among men is but a faint copy (ectype) of this. God so ordered the life of man that the covenant idea should develop there as one of the pillars of social life, and after it had so developed, He formally introduced it as an expression of the existing relation between Himself and man. The covenant relationship between God and man existed from the very beginning, and therefore long before the formal establishment of the covenant with Abraham(Berkhof, Systematic Theology).
Far from being constrained to merely social or horizontal relationships, however, the mutual obligations of the covenant pact is done in the presence of God, and so always has religious significance. Each party is bound to discharge his or her duties, and risk incurring God's covenant curses if the deal is broken. Some may object that one cannot speak of a covenant with mutual obligations on the grounds that the covenant is an unconditional promise of salvation, rather than a mutual pact in which each party is bound to discharge certain duties:
It is perfectly true that both the covenant of works and (as the sequel will show) the covenant of grace are monopleuric in origin, that they are of the nature of arrangements ordained and instituted by God, and that God has the priority in both; but they are nevertheless covenants. God graciously condescended to come down to the level of man, and to honor him by dealing with him more or less on the footing of equality. He stipulates His demands and vouchsafes His promises, and man assumes the duties thus imposed upon him voluntarily and thus inherits the blessings. In the covenant of works man could meet the requirements of the covenant in virtue of his natural endowments, but in the covenant of grace he is enabled to meet them only by the regenerating and sanctifying influence of the Holy Spirit. God works in man both to will and to do, graciously bestowing upon him all that He requires of him. It is called the covenant of grace, because it is an unparalleled revelation of the grace of God, and because man receives all its blessings as gifts of divine grace(Berkhof, Systematic Theology).