Alabama parishoners sang, prayed and cried their defiant support for keeping the monument in the state’s Judicial Building Friday.
A federal court has already ordered the tablet be removed, despite protestations from Alabama Chief Justice Roy Moore.
The dispute highlights an ongoing struggle between Christian conservatives and civil libertarians that dates back more than 20 years.
In 1980, a Kentucky court ruled that displaying the Ten Commandments, revered both by Christians and Jews, in government buildings violated the constitutional separation of church and state.
Since then, the Supreme Court has refused to hear new Ten Commandments cases.
With legal battles being fought in over a dozen US states, religious activists hope to find a Ten Commandments case that can persuade the Supreme Court to break its silence on the issue.
"This has now become the number-one domestic story in America," the Reverend Patrick Mahoney, of the Christian Defence Coalition, told AFP.
Moore had the 1.2 metre monument installed secretly one night some two years ago in the entrance of the Judicial Building.
"There's a religious revival going on"
Christian leaders such as the Rev. Jerry Falwell hope the emotional stand-off Alabama will sway public opinion in their direction.
"I told Judge Moore yesterday that nothing could be better for the cause of religious freedom than that the court send some military or law enforcement personnel into the judicial building in Montgomery with a jackhammer," Falwell told Reuters.
Falwell is infamous for blaming feminists and homosexuals for the terrorist attacks in New York on 11 September 2001.
He said “the pagans, and the abortionists, and the feminists, and the gays and the lesbians who are actively trying to make that an alternative lifestyle, I point the finger in their face and say 'you helped this happen' ”.
Falwell was forced to issue a national apology, after causing a furore across the country.
Experts link support for the displaying of the Ten Commandments to an increasing number of conservative Catholic and Protestant fundamentalists in the US.
The evangelicals are said to represent more than a third of the US population.
“There's a religious revival going on," religion expert Edward Larson told Reuters.
“These people dominated American culture 120 years ago. They lost all of that, but they've regained control in politics since Jimmy Carter was president,” he added.