A carnival float celebrating Thunberg
© REUTERS/Wolfgang Rattay
A carnival float celebrating Thunberg in Dusseldorf earlier this month
From her judging gaze, to her all-or-nothing beliefs, to her unshakeable certainty in her own correctness, the 16-year-old environmental activist evokes unappealing historical parallels.

The journey of Greta Thunberg's activism reads like a Biblical tale: from sitting alone with a placard on a Stockholm street last August, to leading tens thousands of children across the world to walk out of classes on Fridays to protest climate change.

Her doomsday message that there are 12 years left before irreversible temperature rises has been heard from the podiums from her hometown to Davos to Brussels to a UN conference - everywhere the adults marveled.

Thunberg's early protests
One of outside the Swedish parliament in August.
In interviews journalists listen meekly to her mix of messianic proselytizing and harangues for a humanity that has lost its way. Thunberg is vegan, she does not fly by plane, and told the Guardian that with her speeches and organizing duties, she often works 15-hour days.

Her archetype appears to be the medieval child saint: a virgin who chooses death over loss of chastity, or Joan of Arc, an obscure girl struck by visions to command armies.

But you know what. Greta Thunberg is not actually a messenger from God. Her words are not magical. Her youth, purity or lack of doubt are not evidence of her actually being right. Her mission may be righteous or misguided, but has no inherent privilege to sermonize without winning debates.

Environmental activist Greta Thunberg
Environmental activist Greta Thunberg
And the other thing: children's idealism has often fallen victim to or been used as a pawn to quite adult agendas. The children's crusade never did reach Jerusalem, while less apocryphally the Cultural Revolution was also carried out by the hands of bright-eyed youths, convinced they were building a better future. And there are bigger political forces at work here too.

Now, Thunberg hasn't ransacked any ancient temples to purge them of the Four Olds, or ordered petrol cars to be set on fire, and some might say it is bad form to attack a child. But Thunberg has openly used her youth to shame us for supposedly mortgaging her future, and wants us to take decisions with implications for billions of adults, so she has made herself fair game.

There is no call here for her to be burnt at the stake in Rouen. Just a word of caution, where none has been heard.