MERRILLVILLE, Ind. — It is still illegal to buy alcohol at a liquor store on Sunday in Indiana, a red state holding fast to an old blue law.

Grocery stores and gas stations can sell only warm beer, a rule that embeds a sort of mandatory waiting period for impulse drinkers.

But in a state that has some of the quirkiest and most forbidding liquor laws in the country, one of them has been relaxed this year: For the first time in decades, stores and restaurants can sell alcohol on Christmas Day.

In July, a law went into effect that erased a longtime provision that banned the sale of alcohol on Dec. 25. But the law, which will be put to use for the first time on Friday, has set off a quiet rebellion among many Hoosiers who say they would like Indiana to buck a trend toward permissiveness across the country, where most states have overturned blue laws, coffee shops like Starbucks have begun selling wine and beer, and dispensaries have sprouted up to sell recreational marijuana.