The worshippers were slaughtered as they prayed. Their killers stopped only when they themselves were killed. And then some of their co-religionists praised them to the skies, as heroes and martyrs.
I'm describing the appalling, sickening scenes at the Kehilat Bnai Torah synagogue in Jerusalem last Tuesday, when four rabbis and an Israeli police officer were killed in an attack by two Palestinian cousins.
But I'm also describing the equally appalling and sickening scenes at the Ibrahimi mosque in Hebron more than 20 years ago, when an Israeli settler, Baruch Goldstein, opened fire and killed 29 Palestinian worshippers as they prayed. Another 125 were injured.
Israelis rightly reacted with grief, shock and anger at the Jerusalem synagogue attacks, and there are now real fears of a descent into even greater religiously-fuelled violence. And there was particular anger at statements from Hamas, which holds power in Gaza, and the Islamic Jihad movement, which praised the killings and called for more of the same.
Hamas said the attack was in response to the death of a Palestinian bus driver, who was found hanged in his vehicle last Sunday. An autopsy found that he had committed suicide, but a Palestinian doctor who participated in the autopsy has said he believes the driver was murdered. Islamic Jihad said it "salutes the operation in Jerusalem which is a natural response to the crimes of the occupier."
To Israelis, to Jews outside Israel, and indeed to just about everyone else, there is something especially abhorrent about any attempt to justify, let alone encourage, such cold-blooded slaughter in a place of prayer. In an article in the US publication the Atlantic, the leading American commentator Jeffrey Goldberg wrote: "Hamas's endorsement of the massacre of Jews at prayer in their holy city confirms - as if we needed confirming - that its goal is the eradication of Israel and its Jews."
And he contrasted Hamas's praise for the Jerusalem attack with what the then Israeli prime minister Yitzhak Rabin said after the Goldstein massacre in 1994: "You are not part of the community of Israel ... You are a foreign implant. You are an errant weed. Sensible Judaism spits you out." (Rabin was assassinated by an extremist Jewish gunman the following year.)
His disgust was not, however, shared by all Israelis. A quick check with Wikipedia reminds us that to Goldstein's supporters, he was every bit as heroic as the Jerusalem synagogue attackers were to Hamas and Islamic Jihad.
Goldstein was described by one rabbi at his funeral as "holier than all the martyrs of the Holocaust". The epitaph on his gravestone, which to this day is regarded as a shrine by some Israelis, calls him "a martyr with clean hands and a pure heart."
Even more shocking to my mind was an article published in the leading Israeli newspaper the Jerusalem Post in February of this year, on the 20th anniversary of the Hebron killings, written by David Wilder, described as "a spokesman for Hebron's Jewish community".
(Context: Hebron is the largest city in the West Bank, overwhelmingly Palestinian but with a vocal and militant Jewish settler minority. It's where the patriarch Abraham, revered by both Jews and Muslims, is said to be buried, and where in 1929, long before the establishment of the state of Israel, 67 Jews were massacred in one of the worst atrocities of the British mandate era.)
This is what David Wilder, who described Goldstein as a friend, wrote: "Baruch Goldstein was not a bloodthirsty terrorist whose goal in life was to kill as many people as he could, as often as he could. He was a brilliant doctor, whose purpose in life was to save other people's lives. His purpose in life was also to actively support and promote Jewish life in the State of Israel."
He went on to describe Goldstein's murderous rampage as "a tremendously appalling error, which cost the lives of many people, which cost him his own life, and which left an indelible stain on Israel."
And then he continued: "That having been said, and realizing the horror of his act, it must be examined and remembered in the perspective of what was happening around us and to us. Had there not been an intifada, with some 160 Jews killed, with very little government attempts to protect the Jewish victims, he never would have broken and committed the acts that he did. And we cannot and must not forget that what he did, as ghastly as it was, was miniscule compared to the terror and death Israelis have faced at the hands of hundreds of Arab terrorists over the past decades."
Change a couple of words here and there, and it's not hard to imagine friends of Ghassan and Uday Abu Jamal, the Jerusalem synagogue killers, saying exactly the same.
Yes, it's one article, by one man. An extreme viewpoint, not shared by the vast majority of Israelis. But Israelis need to confront a truth that too often is ignored: they too have their zealots, and their murderers. They too have spokesmen who glorify mass murder. When they recoil in horror from the triumphalism of some Palestinian groups, they need to remember - just occasionally - to look in the mirror.
Jerusalem has been at boiling point for several weeks, with many Palestinians angered by calls from some religious Israelis to change the status of the Temple Mount/Haram al-Sharif, cherished by Jews as the site of their ancient temples and by Muslims as the site of al-Aqsa mosque and the Dome of the Rock, the third holiest site in Islam.
I am the son of refugees from Nazi Germany. I am also a former Middle East correspondent who was based in Jerusalem. I grieve for all those killed in both Israel and Palestine in what seems to be an unstoppable cycle of violence. I hope I don't have to spell out that I unreservedly condemn the killing of Jewish worshippers in Jerusalem as much as the killing of Palestinian worshippers in Hebron. And just in case there's any doubt, I'm no fan of Hamas, whose corrupt, brutal rule in Gaza, and whose cynical use of rockets aimed at Israeli civilians, has brought nothing but misery to Palestinians both in Gaza and the West Bank.
Nevertheless, and it gives me no pleasure to write this, it is time for Israelis to wake up, because their complacent belief that the status quo works perfectly well for them is dangerously wrong. Their insistence on voting for political leaders who have no serious intention of seeking a resolution of their historic conflict with the Palestinians is leading them ever closer towards the abyss.
Every time the Israeli government announces a new plan to expand its (illegal) settlements in the occupied West Bank, Palestinians hear the words "we are stealing more of your land". And the longer Israel maintains its vice-like grip on the throats of the people of Gaza - not allowed to leave, not allowed to fish, not allowed to trade - the greater the risk of yet more violence.
The Israeli prime minister Benjamin Netanyahu, who is by no means the most hardline member of his own Cabinet, says Israel will "settle the score with every terrorist" after the Jerusalem synagogue murders. It's the kind of talk that fuels yet more violence, and more hatred. It does nothing to lessen tension.
The sad truth is that Israelis have grown far too confident that their overwhelming firepower - and the continued support of the US Congress - makes them invincible. It does not.