In opening arguments on Tuesday in the trial of four men accused of trying to blow up Bronx synagogues and shoot down military planes in May 2009, there seemed to be little disagreement that the defendants were offered something for joining the plot.

The only question — the central question — was what.

A prosecutor, Adam Hickey, said the men were offered opportunities to commit terrorism, and took them. The man he called the leader of the plot, James Cromitie, “spewed forth hatred and a thirst for violence” in recorded conversations with a government informant, Mr. Hickey said.

“He was not vague; he was not subtle,” Mr. Hickey said. “He said he wanted to do something to America.”

But defense lawyers argued that their clients were a desperate, unsophisticated bunch with criminal records and dim job prospects who were illegally entrapped. They were offered money, the lawyers said, by a polished government informant who drove late model cars, paid for their meals and travel and promised more money when the job was done.

The trial, in federal district court in Manhattan, will be filled with competing portraits of the defendants. Mr. Hickey spoke of their careful planning, while their own lawyers — resorting to slights at times, or outright ridicule — drew a picture of four hapless men who struggled just to get through a day.

More important, defense lawyers will ask jurors to consider the character of the informant, Shahed Hussain, a Pakistani immigrant who told the men he was a terrorist.

Using a strategy that experts say has virtually always failed in terrorism cases since 9/11, the lawyers will argue that Mr. Hussain’s conduct caused the government to cross a line, from a sting operation to an illegal trap.

In June, the judge, Colleen McMahon, postponed the trial after finding that prosecutors had failed to hand over information that should have been given to defense lawyers.

The defendants — Mr. Cromitie, David Williams IV, Onta Williams and Laguerre Payen — face life in prison on charges that include conspiracy and attempting to use weapons of mass destruction and antiaircraft missiles. Prosecutors said the men picked up inert bombs supplied by Mr. Hussain and dropped them off in front of two synagogues, the Riverdale Temple and the Riverdale Jewish Center.

They were arrested near the synagogues, but Mr. Hickey said they had planned to go to the Air National Guard base at Stewart International Airport in Newburgh, N.Y., and use Stinger missiles to shoot down planes.

“They were prepared to go all the way through with their destructive and murderous plan,” Mr. Hickey said. “They were eager to do everything they did.”

But Mr. Cromitie’s lawyer, Vincent L. Briccetti, compared the plot to a “cinematic extravaganza,” saying it was Mr. Hussain, and not his client, who drove it at every turn.

Mr. Cromitie and Mr. Hussain first met at a mosque in Newburgh that Mr. Hussain had frequented for months. It was one of several mosques in the area where he was seen, usually driving one of several expensive cars that Mr. Briccetti said were given to him by the government.

Using “lies, pressure and a whole lot of money,” Mr. Hussain courted Mr. Cromitie, Mr. Briccetti said. He said Mr. Cromitie was a liar “who had a really big mouth,” and Mr. Hussain paid attention. “He likes having this rich friend” who listened to his “cheap philosophizing.”

Mr. Hussain pressed Mr. Cromitie to recruit others to act as lookouts, the defense lawyers said. They included David Williams, originally from Brooklyn; Onta Williams, who is not related to David Williams and had spent time in jail for selling drugs; and Mr. Payen, whose lawyer said was living in a single-room-occupancy residency in downtown Newburgh.

They were offered financial inducements, from meals to a BMW to more princely sums, the lawyers said. Mr. Hussain told Mr. Cromitie by phone: “I can make you $250,000, but you don’t want it, brother,” according to Mr. Briccetti.