As the Divine Liturgy was ending Sunday morning at St. Mark’s Coptic Orthodox Church in Cairo, there was, in the words of one man who was there, a “shattering explosion like nothing I had ever heard before.” The latest reports indicate that 25 people were killed and 49 were wounded as a bomb exploded at a chapel in the cathedral complex. No one has yet claimed responsibility, but there are two principal groups that could have been the culprit: the Muslim Brotherhood and the Islamic State.

“God bless the person who did this blessed act,” wrote one Islamic State supporter about the bombing, and there is always the possibility that the bombers may have been heeding the Islamic State’s call for jihad attacks on Christians worldwide. Last summer, the Islamic State’s Dabiq magazine called for the breaking of the cross, in accord with Muhammad’s purported prophecy that Jesus would return at the end of the world and break the cross. He would do this because the Qur’an asserts that Jesus was neither killed nor crucified (4:157), and consider the Christian idea that Jesus was crucified to be an insult to Allah’s omnipotence.

Christians, said Dabiq, “have the option of trying to cling to the transient luxuries of this life, rejecting the truth in favour of either paying jizyah [tax] to the Islamic State or continuing to wage a futile war against it. Alternatively, they can heed the warning of Allah that the worldly life is not guaranteed even for those who pursue it at the expense of their salvation, and thus choose to embrace Islam, champion the truth, attain the mercy of their Lord, and enter the Gardens of Paradise.” This, too, accords with the Qur’an, which calls upon Muslims to wage war against “the People of the Book,” a group that includes Christians, “until they pay the jizya with willing submission and feel themselves subdued” (9:29).

The Islamic State’s war against Christians and Christianity is thus total and global; the group’s recent jihad activity in the Sinai also make it possible that it could well have struck in Egypt. But it is likewise possible that the perpetrator of the bombing was the great rival of the Islamic State in attempting to restore the caliphate and the glories of political Islam: the Muslim Brotherhood.

As the Muslim Brotherhood regime in Egypt was driven from power in 2013, the anti-Brotherhood protesters accused Obama of supporting terrorism. The accusation wasn’t made lightly. During the Brotherhood’s one year in power, Egypt’s El Nadeem Center for Rehabilitation of Victims of Violence documented 359 cases of torture by the regime — ten times the number of cases documented annually during the Mubarak regime.

One chief Brotherhood target was Egypt’s Christian community: Brotherhood partisans ransacked Christian businesses and abducted Christian children. Brotherhood members blamed the fall of their regime on the Christians and rampaged against Christians all over Egypt, burning and looting nearly seventy churches and destroying 1,000 Christian businesses and homes.

The Rev. Khalil Fawzi of Kasr El Dubarrah Evangelical Church, the Middle East’s largest evangelical church, said: