In my experience, if you ask most newsroom managers and copy-desk pros to name the most important Christian holy day, the majority will say “Christmas.”

Actually, that’s the biggest holiday, from the perspective of the surrounding culture. The correct answer is Easter, the feast of the Resurrection of Jesus Christ.

Now, here is a tricky question — one linked to yet another hellish massacre of Christians in the tense land of Nigeria. What holy day would be ranked No. 2 in the calendar of ancient Christianity?

There may some debates about this, but many historians will say it is the joyous Feast of Pentecost (click here for background material), which closes the great season of Easter. Hold that thought, because we will come back to it. Meanwhile, something very important is missing from the top of this Reuters report: “At least 50 killed in massacre at Catholic church in southwest Nigeria.”

LAGOS, June 5 (Reuters) — Gunmen attacked a Catholic church in southwest Nigeria during mass on Sunday, killing at least 50 people including women and children, according to a hospital doctor and media reports.

The gunmen shot at people outside and inside the church building, killing and injuries worshippers, said Funmilayo Ibukun Odunlami, police spokesperson for Ondo state. She did not say how many people were killed or injured at St Francis Catholic Church in the town of Owo but added police were investigating the cause of the attack.

Ondo state Governor Arakunrin Oluwarotimi Akeredolu, who visited the scene of the attack and injured persons in hospital, described Sunday's incident as "a great massacre" that should not be allowed to happen again. The identity and motive of the attackers was not immediately clear.

The motive was unclear?