Standing with a crowd of around 300 people outside the Massachusetts State House, the Rev. Lydia Shiu of Reservoir Church in Cambridge evoked an enduring metaphor — that of David taking on the giant Goliath in the Bible — as she spoke of the commonwealth's housing challenges.

Shiu helped lead a Greater Boston Interfaith Organization rally Thursday, where the coalition of religious groups and unions called on state leaders to make housing more affordable and accessible. She said the “GBIO sling” had secured past policy wins in health care and criminal justice reform.

“This is not just a housing crisis. This is a human crisis,” Shiu said. “And although the housing crisis purports itself to be a complex and complicated problem — and yes, folks, it is a hairy one — but in the face of Goliath, you cannot mess with the faith and hope of David.”

With its members clad in blue T-shirts, playing trombones, and holding signs with slogans like “Praying with Our Feet,” GBIO launched a new housing justice campaign. The campaign pushes for greater state investment in public housing, zoning reforms to encourage multifamily housing in suburbs, and housing support for formerly incarcerated people.

GBIO also backs legislation that would let communities impose a new fee on certain real estate transactions, with proceeds going toward affordable housing. Under the bills, filed by Cambridge Rep. Mike Connolly and Northampton Sen. Jo Comerford, cities and towns that opt in could impose a fee of between 0.5% and 2% of the purchase price on some property sales.

Municipalities could choose whether the seller or buyer pays the fee, or split it between the two. The fee would kick in only above a certain price threshold: either $1 million, or above the county's median sale price for single-family homes.

Communities including Boston, Somervile, Arlington and Nantucket have sought Beacon Hill's permission to establish transfer taxes in the past, but the concept has faced opposition for years from real estate industry officials, who argue the additional fee would raise costs for buyers.

Phil Hillman, a strategy leader at GBIO and member of St. Paul A.M.E. Church, said the interfaith organization supports transfer tax legislation because it knows new revenue sources will be necessary before communities can create more affordable housing.

"I have seen the impact of this housing crisis on my Dorchester community. This is a type of crisis that has touched family members, friends, coworkers [and] congregations," he said. "For decades, our housing production has not kept up with our job growth. This has resulted in skyrocketing rents, huge increases in housing prices. If you are low-income — lower middle income — the dream of homeownership has become a nightmare."

After rallying outside the State House, GBIO members planned to meet with lawmakers and staff, asking them to support the bills and funding requests that make up the organization’s housing justice campaign.

The organization wants lawmakers to double the amount of money Gov. Maura Healey proposed for public housing in her budget proposal. Healey's budget funds the public housing authorities' account at $92 million for next year, the same amount that was in this year's budget.

At Thursday's rally, Arlene Hill described what it meant for her to move into public housing after spending time at a homeless shelter.

“The ability to lock that door and be in my apartment, with no one telling me I had to do this or that, saved my life,” she said.

GBIO said it will move forward with several action items, and that its members plan to attend committee hearings as lawmakers vet the bills on their agenda.