One who inherits something or who is entitled to a future inheritance. An heir is the one who receives the property of a deceased person, particularly on the basis of law and usually by means of a will. In both the Old Testament and New Testament, the Hebrew and the Greek words encompass these ideas.
In Genesis 15, after God had reiterated his special promise to Abraham, Abraham wondered how the fulfillment of the promise might occur. At the time, only his steward who managed his household, Eliezer of Damascus, was “the son of his house.” That is, the person of his large household who would inherit. There was no natural-born son of Abraham within the family (see Genesis 15:3–4). Without a son in patriarchal times, a man’s chief steward could be his heir as a substitute. Later, after the birth of Ishmael (Abraham’s son by Hagar, Sarah’s maidservant) and of Isaac (his son by Sarah, his wife), trouble erupted between the women. Sarah demanded that Abraham send Hagar and her son away, because Sarah did not want Ishmael to be an heir with her own son, Isaac (Genesis 21:10).
A wise woman, at Joab’s instigation, told David a story about herself and her two sons. She said that one son killed the other, and that her family now wanted to kill the remaining son for the murder. If this happened, she claimed, the heir of her deceased husband would be destroyed and the family would be left with no inheritance (2 Samuel 14:7).
Another biblical illustration of this normal use of the word “heir” is seen in a parable told by Jesus. The workers in the vineyard, who saw the son of their master coming, said among themselves, “This is the heir. Come, let us kill him and take his inheritance” (Matthew 21:33–43; compare Mark 12:7; Luke 20:14).
In multiple references in the New Testament, the word “heir” is used to refer to the believer in Christ. The believer has an inheritance coming because of being a child of God the Father and consequently a joint heir with Christ (Romans 8:16–17). The inheritance of salvation is variously referred to in different sections of the New Testament. In Hebrews 6:17, Christians are called “heirs of the promise.” This promise occurred when God said to Abraham, “I will surely bless you and multiply your descendants” (Hebrews 6:14). In Hebrews 11:7, Noah is described as an “heir of the righteousness that comes by faith.” In James 2:5, the poor in the world who are rich in faith are said to “inherit the kingdom He promised those who love Him.” Paul writes that those who are justified by God’s grace, a declarative act of God by which God establishes persons as righteous, are made heirs according to the hope of eternal life (Titus 3:7).
In Hebrews 1:2, the word “heir” is used with a singular reference to God’s Son, who is said to have been appointed “heir of all things” by his Father. Here is an instance where someone has been designated to receive an inheritance but will enter into full possession of it much later.
In biblical times the right of primogeniture—that is, the right of the eldest son in the family to be the primary heir in the household—prevailed. In Old Testament times, the firstborn son possessed the birthright, which included inheriting a double portion of his father’s possessions and headship of the family (Deuteronomy 21:15–17). The other sons shared the remainder equally. If there were no sons to inherit, the daughters became the heirs (Numbers 27:8; 36:1–12). However, there was a stipulation that the daughters could not marry outside their tribe. This was to preserve the tribal territory intact. If there were no daughters, then the dead man’s brothers inherited. If there were no brothers, then his uncles. And if there were no uncles, then the nearest relative (27:9–11). Because the matter of tribal possession was so important, it is easy to understand why there was such a concern for records of ancestry among the Hebrew people.