He not only thought that he'd be a better ruler than the squabbling Elector Counts of the Holy Roman Empire of the 16th century, but that he was also God's elect.
He considered himself a man chosen by the bloke upstairs to usher in a glorious new age of peace and godliness across Europe.
Jan was an Anabaptist – one of the sects that sprouted like weeds once the Catholic Church was splintered by the Reformation.
His people believed that one could only come to the Kingdom of Heaven by willingly being baptized as an adult.
They also believed in some fairly-forward thinking ideas such as pacifism, freedom of conscience and the separation of church and state – ideas that could get you killed in the early 1530s.
Jan, from the Dutch city of Leiden, came to Münster in 1533 as a result of the danger these ideas had placed him in. He had heard that the city was friendly to Anabaptists and that he'd be able to make something of himself amongst a group of fellow believers.
He heard correctly.
Within months of his arrival, Jan, along with a few of his Anabaptist mates, had seized control of the city, kicking out the city's council and stacking it with fellow believers.
They achieved this mostly by running around the streets in a state of half-dressed religious zeal, singing about the End of Days and the glories that awaited God's chosen ones.
Amazingly, this worked – you have to remember that this was an age of intense religious strife and hysteria. Anyone promising a little peace and prosperity far from the blood and muck of this world was considered worth hearing out.
A bishop strikes back
The fall of Münster to Jan and the Anabaptists did not go unnoticed.
The town's bishop, Franz von Waldeck had been expelled at swordpoint and he was understandably irked.
As the local military, as well as spiritual ruler of the region, he wasn't going to take this lying down.
Bringing in troops and foreign mercenaries, von Waldeck surrounded the city with large earthworks in an attempt to starve out the inhabitants. He also horribly mutilated anyone who tried to break through the blockade as a warning to those within.
Inside the besieged city, Jan's ideas and proclamations became a little more sordid and earthy. Citing scripture, he announced to the good folk of Münster that every woman of marrying age should be hitched.
Never mind that there were less men than women in the city – the blokes would just had to take one for the team and take on a second (and third, and fourth) wife.
Polygamy became the order of the day and there is speculation that orgiastic behaviour started to take hold.
One can forgive Jan and his followers the odd team grope, even stomach his claims of divine wisdom. These hardly distinguish the Anabaptists from a hundred other groups in modern history. We're all guilty of letting power get to our heads at one stage or another.
Where things started to go wrong – to go really quite awful, actually – was when Jan and his followers decided that they had the divine mandate to execute their fellow citizens without trial.
Off with her head
The victims were overwhelmingly women and capital punishment was meted out for some truly ridiculous offenses.
You could lose your head for refusing to marry. Hell, you could lose your head for merely laughing at Jan and his mates.
One of the strangest episodes of the Münster rebellion saw Jan lop the head off one of his sixteen wives, Elizabeth Wandscherer.
She'd had the nerve to call Jan out on his luxurious lifestyle and return the jewellery he'd given her – jewellery he'd looted.
Jan responded by taking Wandscherer into the town's marketplace and executed her, making the crowd sing as he did. He then began to dance around her beheaded corpse, praising God.
Like most crazed cultists surrounded by the forces of law and order, Jan and his Anabaptists couldn't hold out forever. Food, supplies and ammunition started to dwindle and morale sunk.
On June 25th 1535, a disgruntled city refugee called Gresbeck led a large group of very well-armed mercenaries through the defences into Münster.
Once the alarm was raised, the fighting was intense. The bishop's men had to fight their way, street by street until they reached the city square. No quarter was given after months of siege and the streets were slick with gore.
Finally, the core of resistance was broken and the Anabaptists were caught. They were thrown in prison to await trial as von Waldeck consolidated his hold on the city and began to return things to normal.
Death by tongs
On a cold, bright day in January 1536, Jan and his two highest-ranking henchmen were led to a scaffold in the Münster marketplace in front of an audience of von Waldeck, his fellow bishops and a huge number of rubberneckers.
There, pairs of red hot tongs were used to tear pieces of flesh from the bodies of Jan and his colleagues whilst still alive. After a time, all three were dispatched with a dagger to the heart.
Following their execution, the bodies of Jan and his sidekicks were suspended in large metal cages, a reminder to the people of the city not to get any ideas about their station in life.
If you visited Münster, you could still see this reminder. After a time, the cages were suspended from the tower of St Lambert's church where all around could see.
What have we learned? There's plenty to draw from this tale about the danger of cults and falling under the sway of a charismatic leader.
For me, however, it's this – don't annoy a bishop.
By Mike Stuchbery @Mike_Stuchberry
Mike is a teacher and writer originally from Australia and now living in Stuttgart.
Expat Dispatches is a weekly post from an English-language blogger or writer in Germany. It covers everything from lifestyle and food to history and culture. Email firstname.lastname@example.org to have your blog considered for publication.