The image that heralds Solomon Schimmel’s newest book about forgiveness is “The Prodigal Son,” a painting by Marc Chagall. Its central figures are a father and son embracing in a gesture of reconciliation, but Schimmel says forgiveness is hardly this simple.

In the days between the Jewish High Holy Days of Rosh Hashana and Yom Kippur — days that also fall shortly before an unofficial day of mourning in America — Schimmel addressed questions surrounding forgiveness and reconciliation in the Joseph Slifka Center Monday night.

“There’s a difference between justice and revenge, just as there’s a difference between forgiveness and reconciliation,” said Schimmel, who teaches psychology and Jewish education at Hebrew College in Newton Centre, Mass.

Rabbi James Ponet, the Slifka Center’s director, said this point is a crucial one.

“This distinction brings hope to the resolution of current social issues, like the situation in Israel. Perhaps just because I don’t forgive you, it doesn’t mean I have to kill you,” he said.

Schimmel compared Jewish and Christian theological approaches to forgiveness, noting that Christians generally emphasize forgiveness over justice, while the Jewish approach to transgression is more demanding of the sinner.

“In Judaism, there is no obligation to forgive without repentance. Forgiveness can be immoral when it is at the clear expense of justice,” he explained.

He offered the morally open-ended account of a Catholic nun who was gang-raped, beaten and mutilated, but did not press charges against her offenders, and asked if Christianity’s assumption that “forgiveness will change the sinners’ ways” is viable.

Although he did argue that criminals should be imprisoned only for reasons of public safety, not as “revenge” for their actions, he generally offered more questions than answers.

Schimmel and his audience addressed many questions together throughout the exchange — it came to resemble a Socratic dialogue in its quest to define abstract but keenly experienced concepts like forgiveness. But much of Schimmel’s interest in forgiveness seemed culled from history and anecdotes.

Early in the talk, he cited the story of a wounded Nazi soldier who said he needed to see a Jew and be forgiven for his crimes before dying. Simon Wiesenthal — who relates the story in his book “The Sunflower” — was that Jew, and he chose not to forgive. Schimmel asked if Wiesenthal had done the right thing, noting that Wiesenthal himself struggled with that question long after the war’s end.

Responding to a question about current events, Schimmel noted that U.S. President George W. Bush and other government officials “sound very Jewish” in the wake of Sept. 11, and contrasted Bush’s recent public rhetoric with the explicitly forgiving message of Martin Luther King Jr.

“Leaders in the government are not sounding very Christian with their emphasis on revenge over forgiveness. No one is saying we should love Osama bin Laden,” he said.

Despite such grave questions and an anniversary of mass death looming, Schimmel’s discussion was delivered in an informal improvisational manner, and punctuated by moments of humor. When one audience member said he had many questions for Schimmel and did not know which one to choose, Schimmel had a quick solution.

“Read [my] book. Twice,” he said.