For example, Supreme Court Justice James Iredell observed: According to the modern definition  of an oath, it is considered a “solemn appeal to the Supreme Being for the truth of what is said by a person who believes in the existence of a Supreme Being and in a future state of rewards and punishments according to that form which would bind his conscience most.” Signer of the Constitution Rufus King explained: In our laws by the oath which they prescribe, we appeal to the Supreme Being so to deal with us hereafter as we observe the obligation of our oaths.
The Pagan world were and are without the mighty influence of this principle which is proclaimed in the Christian system their morals were destitute of its powerful sanction while their oaths neither awakened the hopes nor fears which a belief in Christianity inspires. George Washington, too, believed that an oath inherently contained a sense of religious obligation. In his “Farewell Address,” he asked: Where is the security for property, for reputation, for life, if the sense of religious obligation desert the oaths?
And John Adams similarly declared: Oaths in this country are as yet universally considered as sacred obligations. Also indicative of this belief is the fact that when the convention of South Carolina ratified the Constitution in 1788, it proposed that in Article VI the word “other” should be inserted after the word “no,” implying that an oath or affirmation to support the Constitution was itself a religious test. Numerous other sources further illustrate the fact that the taking of an oath presupposed a belief in God. For example, the 1799 Kentucky Constitution declared: The manner of administering an oath or affirmation shall be esteemed by the General Assembly the Legislature the most solemn appeal to God.
Other constitutions contained the same declaration. Chancellor James Kent a Father of American Jurisprudence noted that an oath of office was a “religious solemnity” and that to administer an oath was “to call in the aid of religion.” In the case People v. Ruggles (1811), Kent ruled that “Christianity was parcel of the law and to cast contumelious insulting reproaches upon it tended to weaken the efficacy effectiveness of oaths,” again affirming the intrinsic relationship between taking an oath and a belief in God.