Two people were killed and 20 wounded, all of them Christians, according to the Ministry of the Interior. The bombs were placed near the homes of at least 14 Christian families around the city, and four bombs were defused before they could explode.

Christians have been flooding out of the country since the siege of Our Lady of Salvation, a Syrian Catholic church, in October that left nearly 60 people dead, including two priests. Many Muslim clerics and worshipers offered support to Christians after the siege. The Islamic State of Iraq, an extremist group affiliated with Al Qaeda, claimed responsibility for the attack, and on Dec. 22 it promised more on its Web site.

For some Christians here, the latest attacks represented the last straw.

“We will love Iraq forever, but we have to leave it immediately to survive,” said Noor Isam, 30. “I would ask the government, ‘Where is the promised security for Christians?’ ”

Even before the coordinated assault, Baghdad had come to resemble a battle zone for Christians, who have come increasingly under attack since the American-led invasion in 2003. Before Christmas, several churches fortified their buildings with blast walls and razor wire, and many canceled or curtailed Christmas observances. The day passed without an attack.

At the Sacred Church of Jesus, a Chaldean Catholic church, the Rev. Meyassr al-Qaspotros said Thursday night that he would urge followers not to flee after the latest attacks.

“I just wonder, when does this ignorance end?” he said in an interview. “When does this bigotry end? When is there an end to weak-minded people not treating or thinking of other people as a human?”

He added, “I want to tell the Christians in Iraq not to leave their country despite the dangers. Let’s die here — better than living oppressed in another country. It’s our responsibility to sacrifice for this country in order to take it out of the deep hole and to live peacefully again among the people of Iraq as we used to live before, and even better.”

Since October, at least 1,000 Christian families have left Iraq for the relative safety of semiautonomous Kurdistan in the north, and others have sought refuge in Syria, Turkey and Jordan, according to the United Nations. By most estimates, more than half of Iraq’s Christians have left the country since 2003. Though the exact size of the Christian population is unclear, by some estimates it has fallen to about 500,000 from a high of as many as 1.4 million before the American-led invasion.

The bombings occurred within a span of a half-hour between 8 p.m. and 9 p.m. on Thursday, according to the Ministry of Information. The first bomb exploded near a house in the Jadeeda neighborhood, killing two people and wounding three. The other explosions were less lethal, but all resulted in injuries.

No one immediately claimed responsibility for the attacks.

During the siege in October, the Islamic State of Iraq said on its Web site that the assault was in response to actions by the Coptic Church in Cairo, where the wives of two priests had tried to convert to Islam to escape their marriages; the militant group asserted that the church was holding the women against their will and forcing them to convert back to Christianity. It called for their release and threatened more violence if its demand was not met.

In Cairo on Wednesday, the Coptic pope said in a sermon that the threats against the church were both a blessing and a curse, because they had brought Egyptian Christians and Muslims together, according to the Arabic news agency Al Arabiya.

In response to the coordinated bombings in Baghdad, Younadim Yousif, a Christian member of Iraq’s Parliament, blamed the security forces for failing to prevent the attacks, especially after the extremist group had announced its intentions. “The government bears full responsibility for these attacks, because they already promised to secure the Christians,” Mr. Yousif said.

“I think there is complicity by security forces helping insurgents to implement their attacks, because it is unbelievable that they could plant more than 10 I.E.D.’s in different areas targeting Christians,” he said, referring to improvised explosive devices.

Maj. Hashim Ahmed, a police investigator, said the broad scale of the attacks surprised security forces. “The failure of our commanders and the government was clear, because they didn’t take serious measures,” he said.