The Hebrew word berith denotes an arrangement between two parties, e.g. Abraham and Abimelech (Gen. 21: 25 ff), but the OT is largely the story of a covenant, or agreement, between God and the people of Israel. There was such a covenant with Noah (Gen. 9: 8) by which God promised there should never again be a universal flood. Certain conditions were imposed (Gen. 9: 4–6), but in general the OT stresses the element of grace on the part of God, as in the case of the covenant with Abraham (Gen. 17: 8), which was sealed with the promise of regular circumcision (Gen. 17: 23). The covenant at Sinai is more clearly a conditional type of covenant. Thereafter the mutual responsibilities between God and the people is a constant refrain in the history. The account of its establishment in Exod. 19 and the probably more ancient tradition in Exod. 24 may show similarities with arrangements made in treaties between states, e.g. the Hittites in the ancient Near East. Both accounts recognize the saving acts of God for Israel and demand obedience of the people to the Law in all its ramifications. The agreement or treaty is said to be deposited in the Ark of the Covenant (Exod. 25: 16), very much as in other nations treaties were deposited before their idols. A ceremonial meal followed (Exod. 24: 9–11) by way of ratifying the covenant.
The details of the covenant made with Moses are contained in ‘the book of the covenant’ (Exod. 24: 7) spelt out in Exod. 21 and 22.
There was also a promise type of covenant between God and David, assuring him of the permanence of his dynasty, subject to its obedience to the Law (1 Kgs. 2: 4; Ps. 132: 12), and popular belief in this covenant led to an expectation of the nation's security, which the prophets tried to disabuse. Obedience to the stipulations of the covenant at Sinai was, for them, basic, and when Israel broke the terms of the covenant the agreement could be temporarily rescinded by God. Jeremiah predicted that in due course there would be a restoration and a new covenant (Jer. 31: 27–37), when its form would be different, being part of the inward nature of individual Israelites. As such, it would be unbreakable.
The NT sees this new covenant established by Jesus (Mark 14: 24; 1 Cor. 11: 25), and Christians are the human party to this new covenant (2 Cor. 3: 6), a theme especially worked out by the letter to the Hebrews (Heb. 7: 22; 8: 8–13). Paul regards the covenant promise to Abraham as fulfilled in God's grace in sending Jesus Christ (Gal. 3: 6–18), and the promise to David (Isa. 9: 7) could be used as one OT basis for proclamation of Jesus as Messiah.