The resounding shrieks of the fire alarm interrupted Mara Willard as the lecturer on religion and society welcomed a guest speaker to the Harvard Divinity School Wednesday night. As a student ran to check whether the alarm was a test or an actual threat, the speaker, Sister Simone Campbell, seized the opportunity and the microphone.

“Can I tell a joke?” Campbell said, as audience members looked around with bemusement. “My friend gave me this Joan of Arc figurine a while ago,” she continued over the blare. “Written on it was a little message: if invited to a fireside chat, keep moving.”

There was no fire, just a bit of chaos, and Campbell, the executive director of the progressive Catholic organization NETWORK, carried on with the third and final lecture of the Divinity School’s Religion and American Public Life series.

In addition to emphasizing the importance of unity in the face of economic, political, and social instability, Campbell discussed her “Faithful Budget,” a spiritually based alternative to the budget proposed by Congressman Paul Ryan, Mitt Romney’s running mate. This summer, Campbell led a nine-state “Nuns on the Bus” tour, joining with sisters from around the nation to caution the Catholic community against what she said was an “immoral” budget plan that would hurt the poor.

Campbell took advantage of the fire drill to make her presentation interactive. When the audience was temporarily displaced to the Divinity School courtyard, she created a makeshift aisle—to maintain the lecture’s religious feel, she said.

She then recruited seven volunteers to form a “human bar graph,” to demonstrate the disparities in income created by the nation’s “trickle down” economics.

“The theory of trickle down economics is obviously a failure, or else it takes an exceedingly long glacial age to trickle down,” Campbell said.

With the alarm finally silenced, the lecture resumed indoors.

“My friends, this is the challenge we’re facing as a nation,” Campbell said.

“We’re no longer connected enough as people to know what’s happening to each other,” she added. “The distances have become too huge for us to know each other’s struggles.”

Turning to her “Faithful Budget,” Campbell said it can be reduced to five words: “reasonable revenue for responsible programs.”

Her plan calls for higher income taxes on the top earners and greater funding for social services.

The lecture attracted both Divinity and Kennedy School of Government students.

“Sister Simone puts the unspoken truth into public discourse,” said Casper R. ter Kuile, a Kennedy School student.