Richard McFarlane appeared in Edinburgh Sheriff Court dressed in a purple kilt, black leather jacket, Scotland rugby top and with bright blue paint covering his face.
The former soldier was soon put in his place when Sheriff John Cook compared him to the blue cartoon characters and ordered him to wipe his face clean before his trial could start.
Following a short break McFarlane, 55, returned to the dock where he defended himself against an allegation of sending the threatening note to Ms Sturgeon.
The three-page rant was filled with references to former SNP Finance Minister Derek Mackay being “a poofter” and contained several biblical quotations.
McFarlane, from Bellshill, Lanarkshire, also stated he believes homosexuality “leads to paedophilia which leads to bestiality”.
The letter said: “Nicola I have written to you before in good faith. There are only two genders, p*****y is wrong, please in the name of Jesus, follow not the p*****r script.
“You are deliberately allowing yourself to be used to promote a Satanic agenda.”
The abusive letter also described the LBGTIA-Z community as “a Marxist organisation”.
A Scottish government worker who opened the mail at the capital’s St Andrew’s House on February 17, 2020 spotted the alarming comments and called police to investigate.
During his trial McFarlane failed to ask any questions of the witnesses but made a long rambling speech to the court claiming “Christ is on his second coming”.
He said: “The letter was motivated because I felt Our Father motivated me to tell Nicola, not out of hatred but out of love.
“I wrote the letter because I believe Christ is on his second coming and I felt that with the minister for finance I felt somewhat annoyed he was continuing with his job in the Scottish Parliament and claiming thousands of pounds in expenses.
“I felt at the time I really needed to say to Nicola that guy getting sacked didn't go far enough. He should have not been an MSP anymore.”
The unemployed HGV driver then completed his address to the sheriff by reading out the hymn ‘Once To Every Man And Nation’ written by James Russell Lowell.
Sheriff Cook found McFarlane guilty of behaving in a threatening or abusive manner by sending the letter to Nicola Sturgeon which contained homophobic and threatening remarks.
McFarlane asked the sheriff not to issue a fine due to his financial constraints and instead asked to carry out unpaid work in his local community.
Sheriff Cook agreed and deferred sentence to next month for social work reports.
Speaking outside court, McFarlane said he thought the sheriff was “very fair” in his judgement and he was “fairly happy” at how the trial went.
He said: “I told the sheriff I was identifying as William Wallace but he said I should consider my position coming into his court looking like a Smurf.
“To be fair I knew he was going to find me guilty, but it comes down to people’s perceptions.
“I admitted I wrote the letter but it was just a wee dig at Nicola.”