Definition
One who does not believe in, or who denies, the existence of God. The term carries no special legal meaning beyond this descriptive sense, but it acquired significant procedural consequences at common law — most importantly, the rule that an atheist was incompetent to testify as a witness in court.
The legal significance of the term is almost entirely historical. At common law, the competency of a witness to give sworn testimony depended on the witness holding a belief in God and, critically, a belief in divine punishment for false swearing. An atheist, lacking both, could not take an oath in any legally cognizable sense and was therefore excluded from giving testimony altogether.
Common Language
Modern common usage (Wiktionary): "Of or relating to atheists or atheism; atheistic." (As a noun, one who disbelieves in the existence of God or gods.)
Historical common usage (Webster's 1913): "One who disbelieves or denies the existence of a God, or supreme intelligent Being. A godless person."
The ordinary meaning and the legal meaning of the term are not in conflict — the legal definition tracks the common one closely. The gap lies elsewhere: in ordinary usage, the word carries no procedural weight, while in historical legal usage it was a formal category of witness disqualification with direct consequences for litigation. A researcher who treats the term as merely descriptive when reading historical sources will miss its operative legal force.
Common Confusion
Atheist was not always carefully distinguished from infidel in historical legal sources. Infidel was the broader common law category — encompassing any person whose religious beliefs were deemed insufficient to support a binding oath, including adherents of non-Christian faiths. Atheist referred specifically to one denying God's existence altogether. Anderson's Dictionary of Law cross-references INFIDEL directly. In some older authorities the terms are used interchangeably; in others, the distinction matters because the treatment of, for example, a Muslim or Jewish witness differed from that of a declared atheist. Researchers should not assume the terms are synonymous when encountered in historical pleadings or evidence treatises.
Why It Matters in Research
The legal significance of this term is almost entirely historical and confined to the law of evidence. Researchers working in pre-twentieth-century sources — particularly in treatises on evidence, records of witness challenges, and competency proceedings — need to understand that an atheist's disqualification was not merely social prejudice translated into practice but a formal doctrinal rule grounded in the theory of the oath. The oath derived its legal force from the witness's belief in divine sanction for perjury; without that belief, the oath was considered void and the testimony worthless.
This rule was modified over time, first by statutes allowing affirmation as a substitute for oath, and later by broader competency reforms in the nineteenth century that progressively decoupled witness competency from religious belief. In the United States, this transformation proceeded unevenly across jurisdictions. The cases cited in Black's 2nd edition — including Massachusetts decisions — reflect an era when courts were actively working through the limits of the atheist disqualification rule. By the late nineteenth and early twentieth centuries, most American jurisdictions had abolished the rule by statute, though the transition dates vary.
A researcher reading trial records, depositions, or evidence challenges in sources predating these reforms must be alert to the possibility that a witness described as an atheist was being challenged on competency grounds, not merely characterized in passing. The label had real procedural stakes. Researchers should also note that the rule created incentives for parties to contest a witness's beliefs as a litigation tactic, meaning historical uses of the term in court records may reflect strategic framing rather than genuine religious inquiry.
The term appears rarely in modern legal sources except in constitutional contexts — Free Exercise and Establishment Clause doctrine has addressed the equal treatment of atheists and religious believers — but those constitutional dimensions are not what the historical dictionary sources are addressing.
Historical Dictionary Support
The historical dictionaries are in close agreement on the core definition and its principal common law consequence. Black's (both editions), Bouvier's, Rapalje & Lawrence, Burrill's, and Anderson's all define an atheist as one who disbelieves in or denies the existence of God, and all but Black's first edition explicitly note the witness incompetency rule.
Bouvier's is the most detailed, stating that atheists are "incapable of giving testimony under oath" and specifying that witness competency requires belief in punishment for false swearing "either in this world or the next." This formulation is significant: it clarifies that the operative legal concern was not belief in God per se but belief in the binding force of an oath — a slightly different test that explains why the rule could be applied with varying results depending on how narrowly or broadly courts construed a witness's stated beliefs.
Anderson's is notable for cross-referencing INFIDEL, OATH, and RELIGION, signaling that the term was understood as part of a cluster of related competency concepts rather than a standalone definition. Burrill's preserves the distinction between "does not believe in a God" and "denies the existence of God" — a philosophically meaningful difference that courts occasionally examined.
What the historical dictionaries largely omit is the trajectory of legislative reform. They state the common law rule without flagging that it was already being eroded in some jurisdictions at the time of their publication. Researchers relying solely on these entries for the state of the law in any given jurisdiction or period should consult period evidence treatises and applicable statutes directly.
Jurisdictional Note
The common law disqualification of atheist witnesses was modified at different times in different American states, primarily through nineteenth-century evidence reform statutes. England addressed the issue through a series of oaths statutes culminating in the Evidence Amendment Acts. Researchers working across jurisdictions should not assume a uniform date of abolition; the rule persisted longer in some states than others.