In Ms. Lange, the institute found an experienced legislative tactician and a disarming public face. Ms. Lange grew up in Peoria, Ill., as a regular churchgoer and youth-group member in a United Methodist congregation. While she recalls having decided by her early teens that she did not believe in God  and being particularly disturbed by what she considered the misogyny of the Bible  she still accompanies her parents to church during family visits to the Midwest.

She put her idealism first into the Peace Corps, spending two years in Guatemala, and then into the presidency of the National Organization for Women’s chapter in Buffalo. (In somewhat unfeminist fashion, she had followed a boyfriend to western New York.) She then became a legislative aide to Sam Hoyt III, a Democratic assemblyman from Buffalo, serving two years in his district office and then three in Albany.

Her time in the state capital gave her the practical savvy and personal connections that the humanist institute sought when it hired her last April. As Ms. Lange zigzagged through the office building on that Monday morning this month, she collected busses on the cheek and doting questions about her toddlers, Hannah and John. Her fond relations with the secretaries and administrative assistants ensured that she would get access, timely access, either to legislators or a staff member of consequence.

“Being an insider, I know who you need to know,” she said. “I know the process. The bills, the legislation, the budget, scheduling meetings.”

At each stop, Ms. Lange made her pitch against the Religious Freedom Restoration Act. While the measure sought to remove any “unreasonable burdens” from religious practice, the State Constitution more than amply protected religious freedom, she told legislators. A new law risked eroding the separation of church and state.

In her search for allies, she made sure to discuss issues like same-sex marriage and comprehensive sex education, on which she and many legislators already agreed. She also lined up sponsors and votes for a coming resolution to declare Feb. 12 as Darwin Day. (It passed unanimously.)

Still, none of the five Assembly members she met with promised to side against the religion measure. Mr. Brodsky, a Democrat from Westchester County, chided Ms. Lange that opposing the bill put her on the same side as lobbyists for fundamentalist Christians and ultra-Orthodox Jews, who deemed the measure too weak.