Presidential inaugural addresses are unpredictable, but it's a good bet that they will refer to the Bible. President Biden did, quoting Psalm 30:5: "Weeping may endure for a night, but joy cometh in the morning." This is part of a welcome, long-running trend toward more religious language in public life.
Mr. Biden has cited Psalm 30 in speeches before, and it seems particularly apt in these dark times. Mr. Biden also encouraged his fellow Americans to "open our souls instead of hardening our hearts," an allusion to God hardening Pharaoh's heart, beginning with Exodus 7:13.
With these references, 27 out of 45 presidents have cited the Bible in their inaugural addresses, making a total of 64 biblical references. Forty-four came from the Hebrew Bible and 20 from the New Testament. John F. Kennedy, the only Catholic president before Mr. Biden, made the most allusions in one speech, with five. He referenced the Hebrew Bible and the New Testament, including Isaiah 58:6's call to "undo the heavy burdens . . . and to let the oppressed go free" and Romans 12:12's "rejoicing in hope, patient in tribulation."
The tradition of biblical allusions in inaugural addresses dates back to the beginning of the Republic, when George Washington made an argument for them. In his first inaugural, Washington referred to Psalm 82. "It would be peculiarly improper," he said, "to omit in this official act my fervent supplications to that Almighty Being who rules over the universe, who presides in the councils of the nations."
Somewhat more surprising is the biblical reference from Thomas Jefferson, a deist who famously excised from a Bible any references to Jesus ' divinity. Jefferson spoke hopefully of a chosen country with "room enough for our descendants to the thousandth and thousandth generation," an allusion to Exodus 20:6.
The most famous presidential Bible reference is probably Lincoln's opening to the Gettysburg Address, with "Four score and seven years ago." It's a nod to Psalm 90:10's description of a man's lifespan as "threescore years and ten; and if by reason of strength they be fourscore years." Lincoln also folded religious references and biblical verses into his inaugural speeches. In his first, in which he argued against those who might destroy the Union, he appealed to the "better angels of our nature." In his second, he cited the Bible multiple times, including Genesis 3:19's "wringing their bread from the sweat of other men's faces," Matthew 18:7's "Woe unto the world because of offenses," and Psalm 19:9's "the judgments of the Lord are true and righteous altogether."
Although the U.S. has grown increasingly secular and religiously diverse, biblical references were less common earlier in American history. In the 29 speeches from Washington through William McKinley's second inaugural in 1901, only 11 alluded to the Bible. The frequency has increased since, with 23 of 30 speeches making a biblical reference.
The increased tone of religiosity may reflect a greater comfort with religion in the public square, as Americans have become less concerned over the prospect of state-established religions the likes of which the Pilgrims and other migrants fled. Additionally, both parties appreciate the Bible's political power. Republicans tend to quote the Bible because their constituents tend to be more religious. Democrats often use it to indicate they aren't as secular as their party's reputation suggests.
Biblical allusions are not risk-free. When one does cite the Bible, it is best to be genuine about it. Few Americans saw Donald Trump as a deeply religious man—a reputation he solidified in 2016 by referring to "two Corinthians" instead of "Second Corinthians." And Mr. Biden, despite his frequent biblical references, recently pronounced "Psalmists" as "palmists." Gaffes like these can lead the religious and secular alike to wonder reasonably about political leaders' sincerity.
In citing the Bible in his inaugural address, Mr. Biden has continued a venerable and valuable presidential tradition, one that shaped the country's cultural vocabulary for more than two centuries. Even in an ever more secular world, there's still value in referencing such timeless words.