QUINCY — A Massachusetts judge just slammed the brakes on a city plan to install two towering Catholic saint statues outside Quincy’s brand-new public safety building — in a showdown that’s quickly turning into one of the state’s most explosive church-and-state battles in years.

The ACLU of Massachusetts celebrated the ruling as a “major win for the separation of church and state,” after the court granted a preliminary injunction halting construction of 10-foot bronze monuments to St. Michael and St. Florian — the patron saints of police and firefighters — while the lawsuit plays out.

The city, led by Mayor Thomas Koch, had budgeted a jaw-dropping $850,000 for the project, arguing the statues were simply meant to honor first responders. But a group of Quincy residents backed by the ACLU, Americans United for Separation of Church and State, and the Freedom From Religion Foundation called foul, saying the plan crossed a constitutional line and effectively turned a government building into a shrine.

In the court’s view, the case wasn’t as holy as City Hall hoped. The judge agreed that the plaintiffs raised serious concerns — warning that placing explicitly religious symbols on a government building could make non-Catholics wonder if they’d get equal treatment from the very agencies meant to protect them.

For now, the statues will stay boxed up while lawyers on both sides prepare for what’s shaping up to be a political and cultural showdown in blue-collar Quincy — a city where Catholic roots run deep but constitutional limits run deeper.

Mayor Koch has yet to back down, vowing the saints were meant to “honor those who serve,” not proselytize. But critics say the case could set a national precedent, testing just how far Massachusetts officials can go when faith meets government steel and stone.