Phillip Thompson has received messages of support, thanking him for his honesty, after he apologised for a 2012 Facebook post in which he threatened harm to Muslims.
Mr Thompson said he wants to come clean about his past and admit to his mistakes, ahead of the federal election in May.
The 2018 Queensland Young Australian of the Year is running in the most marginal Labor-held seat in the country, Herbert, in the Queensland city of Townsville.
Queensland Young Australian of the Year winner Phillip Thompson with other award winners. Source: AAP
He served in the military before he was discharged in 2012 due to physical injuries and mental health issues.
That same year he posted remarks on his private Facebook account in which he threatened to harm Muslims.
The post reportedly said: "...a sign said behead all those who insult the profit (sic) i know what im (sic) doing this week getting my GUN licence" and "give me a M4 and send to Sydney and I'll do the dishes".
The comments were a response to Sydney protests triggered by a US film, Innocence of Muslims, which depicted the prophet Muhammad as a womaniser and a paedophile.
LNP candidate for the seat of Herbert, Phillip Thompson, with Prime Minister Scott Morrison. Source: Facebook
"Seeing people holding signs calling for beheading in Australia, at the time I saw the people I was fighting in Afghanistan," he told reporters in Townsville.
"And that is the thing with post-traumatic stress disorder you can really fixate on things like that. As well as the heavy drinking. Making comments is something I shouldn't have done, and I won't do again.
"...I am very apologetic for any distress I may have caused with my comments."
Mr Thompson said he wants to be honest with Townsville voters about his past, including his struggle with post-traumatic disorder.
"I am not a career politician. I want to be open and transparent with the people of Townsville," he said in a video posted on his Facebook page.
"I've made mistakes, but that is not the person I am today."
Phillip Thompson's supporters and campaign team. Source: AAP
He said he has now come clean about his past in a way that voters can make an informed vote.
"I was in a bad place. I am now being open with Townsville about social media posts that I have made and that I am not proud of.
"I am an open book. And I am here to tell the people of Townsville [about myself] warts and all."
His wife, Jenna, said she was proud of how far he has come.
"It was a difficult time for us going through post-traumatic stress disorder. But I am proud of Phillip's growth in that time. And the man he is today is definitely not the man he was back then."
Mr Thompson said the LNP is well aware of his struggle in the past with PTSD.
"The LNP has known about my PTSD, have known about the struggles I have had. It is about being open and honest with the people in the electorate you want to represent."
LNP candidate for the seat of Herbert, Phillip Thompson addresses the media at the Port of Townsville. Source: AAP
People posted messages of support on his page, thanking him for his honesty and willingness to own up to his mistake.
"Mate, the difference between yourself and career politicians is that you have lived in the real world," Jared Patch wrote.
"You have hit rock bottom and clawed yourself back out through hard work and determination. You are what most would consider a role model for people suffering mental illness, that you can still achieve goals with mental problems."
Mick Preston echoed similar sentiments, writing: "Well done we have all made mistakes good on you for speaking the truth and good luck for the future."
Mr Thompson urged any soldiers who experience thoughts of ill will towards others to seek help from Open Arms and family, rather than vent on social media.
Businessman Clive Palmer is also expected to run for the seat of Herbert at May's election.
