A "lost" Bible belonging to Abraham Lincoln that's now on display at the Abraham Lincoln Presidential Library and Museum in Springfield, Illinois may shed new light on his religious beliefs (or lack thereof), which scholars continue to debate.

The Ladies of the Citizens Volunteer Hospital of Philadelphia gave the 18-pound book to Lincoln in 1864 when he visited the city to raise money for soldiers' medical care. According to Smithsonian.com, after Lincoln's assassination in April 1865, Mary Todd Lincoln gave the Bible to the Reverend Noyes W. Miner, a close friend and neighbor of the Lincolns who helped transport Lincoln’s body from Chicago to Springfield and read at his funeral.

Historians were unaware of the Bible's existence until recently. Miner family members passed down the Bible for 150 years before donating it for public view, a decision they made after visiting the museum last year and being moved by the staff’s devotion to the history of the reverend and his involvement in Lincoln’s life, reports the Chicago Tribune.

Lincoln, who was raised as a Baptist but was never actually baptized, is one of only two presidents with no formal religious affiliation—the other was Thomas Jefferson.

Though Lincoln didn’t hide his skepticism in his early life and political career, some historians believe that the deaths of his two sons and the fight to end slavery elicited belief in the likelihood of a divine plan. Allen Guelzo, author of Abraham Lincoln: Redeemer President, told History.com that Lincoln even told his Cabinet that he intended to issue the Emancipation Proclamation because he had vowed to God that if the Union Army won against the Confederates in Maryland (which happened at the Battle of Antietam in 1862), he would do so.

Mary Todd Lincoln, whose own spirituality has been well documented through her fondness for séances (which her husband may have attended at least occasionally), insisted that Lincoln was deeply religious. It’s also possible that Mary’s seemingly sentimental gift to the reverend was an effort to establish Lincoln's Christian credibility.

[h/t Smithsonian]