CAIRO — Grief and rage flowed through Egypt’s Christian community on Monday as tear-streaked mourners buried the victims of the coordinated Palm Sunday church bombings that killed 45 people in two cities. The cabinet declared that a state of emergency was in effect. A newspaper was pulled off newsstands after it criticized the government.

It was just the reaction the Islamic State wanted.

Routed from its stronghold on the coast of Libya, besieged in Iraq and wilting under intense pressure in Syria, the militant extremist group urgently needs to find a new battleground where it can start to proclaim victory again. The devastating suicide attacks on Sunday in the heart of the Middle East’s largest Christian community suggested it has found a solution: the cities of mainland Egypt.

Since December, the Islamic State, also known as ISIS, has signaled its intent to wage a sectarian war in Egypt by slaughtering Christians in their homes, businesses and places of worship. Several factors lie behind the vicious campaign, experts say: a desire to weaken Egypt’s authoritarian leader, Abdel Fattah el-Sisi; a need to gain a foothold in Egypt beyond the remote Sinai deserts where jihadists have been battling the army for years; and a desire to foment a vicious sectarian conflict that would tear at Egypt’s delicate social fabric and destabilize the state.

“There’s a significant propaganda factor to this,” said Mokhtar Awad, a militancy expert at George Washington University. “ISIS wants to show that it can attack one of the Arab world’s most populous countries.”