Good Friday is the only Christian holiday that causes me to stop and think — about such disparate matters as dangerous ideas and the calendar. Sometime on this day between noon and 3:00pm, I try to remember that these are the hours during which Jesus may have hung on a cross and died.

Most of what I know of Christian theology comes from studying the history of western art which requires familiarity with the Bible as an iconographic source. Therefore, Tintoretto’s Christ before Pilate provides an image for me of Jesus’ trial although his judges may also have included Herod Antipas, the Roman authority in Galilee and a brother of the Herod of the Passover story, and possibly a Jewish Sanhedrin. Certainly both the Romans and the Jews had reasons to be concerned about the following this young Jew was attracting to his ideas that challenged existing beliefs.

And that’s the idea that I consider annually on Good Friday: we kill people for what they profess, even when or perhaps especially when, they challenge the status quo.

The religion that grew out of Jesus’ death is no exception. Galileo, for one, was declared a heretic by the Inquisition in the 1560s for his statement that the earth circulated the sun. Talk about a dangerous idea! While Galileo didn’t loose his life, he lost his intellectual and physical freedom, and was forced to recant his views. What do retributions like these for one’s ideas say about humankind?

Unsure how to answer that, I segue-way to another knotty issue: the unorthodox way in which the date for Easter is calculated. Passover and Easter were tied as holidays even before the gospels narrating the Easter story were written. They all (I think) say that the crucifixion takes place in the early days of Passover. But when is that? Jews use the lunisolar Hebrew calendar to determine the dates for Passover. Western Christians, who normally use a solar calendar and therefore follow fixed dates for holidays, make an exception for Easter that mimics a lunisolar calendar. Easter falls on the first Sunday after the paschal full moon, an ecclesiastical event, that occurs on or after the vernal equinox, an astronomical event.

Three of the four gospels — John of course being the exception —  describe a darkened sky while Jesus hung on the cross (see Veronese’s Calvary below) . This is highly likely to have been a dramatization of the mood by the evangelists — or maybe a rain storm as we had today, but certainly not a solar eclipse has some have argued. A solar eclipse is not possible when the moon is full. No matter what the date, Easter and Passover happen at the time of a full moon.

The events as told in the gospels that follow the crucifixion are the ones that give this holiday its meaning. But I’m finished with my observations after 3:00 pm on Good Friday. If I’m lucky, the sky will be bright with a post equinox sun in the coming days. I’ll put on my garden clothes and hunt for signs of plant regeneration, safe from most dangerous ideas.