She said: "This week has seen the really ugly spectacle, of a bunch of men asserting their right to rape women, handmaidens supporting that right and both of them sending out a clear warning to all other rape victims, to know what to expect if they dare to pursue justice if they are raped."
The poster added that the rhetoric inferred that "that if a man rapes you, it is because you are a sl*t, a sl*g and all the other hate-speak words used to de-humanise women and make it easier for people not to empathise with us when we are abused."
Members of the forum have now called for the FA to publicly pledge to "work as hard to kick sexism out of football as they do to kick racism out".
Commentators on Twitter are also showing their support using the hashtag #Ibelieveher
Their public display is largely in response to Facebook groups set up to support Evans.
One, entitled "Securing an immediate retrial for Ched Evans", states: "It is our firm belief that Ched is innocent and, as such, we are therefore seeking to redress this miscarriage of justice."
A member wrote: "Oh my god that has so upset me 2 no hes having a bad day come on ched keep strong we r 4 u all our love and wishe r with u super ched xx." (sic)
Another said: "keep it goin we support free ched my bro n girlfreind n freinds r goin to match n wik b showin support free ched." (sic)
Others said simply: "Justice for Ched."
One Mumsnet member wrote on the forum: "To have gone through the rape itself, to have the courage and strength of will to make it through a court case, only to be the victim of the most hateful abuse afterwards, must be soul destroying. I believe her."
Another said: "I believe her. So did the police. So did the CPS. So did the jury.
"She has done nothing wrong and I really hope she has some great supportive people around her."
Justine Roberts, Mumsnet founder, said the website have already been running a campaign called We Believe You, following a survey of members which found many had not reported their own sexual assaults.
She said: "The case has grabbed people's attention mostly because of the reaction on Twitter afterwards, where the victim was named and there were questions over whether Evans should have been convicted.
"Mumsnet members have wanted to show support to her and express their feeling that naming her was outrageous. They want to let her know that what he did was wrong and that they stand behind her.
"We are really hopefully the We Believe You campaign will be taken seriously as an issue."
More than 3,500 people have already signed an online petition to have Evans removed from the Professional Footballers Association(PFA) League One team of the year.
The campaign, started by secondary school teacher Leo Hardt, warns that young people see footballers as role models and calls on the PFA to "ensure that the public see them upholding certain values about sports professionals"
Ched Evans, 23, has been jailed for five years for raping a 19-year-old woman who was "too drunk to consent to sex" as two of his friends watched and tried to film it on a mobile phone.
His co-defendant, also a footaller, was found not guilty of the same charge, relating to a night out in Rhyl, north Wales, last May.
The court heard that both men admitted they had sex with the woman, who cannot be named for legal reasons, but the prosecution said she was too drunk to consent to sexual intercourse.
In her evidence to police, the woman said she has no memory of the incident and believes her drink may have been spiked.
A minority of Sheffield United fans had planned a public show of support for jailed Evans, by clapping during specific minutes during their match at the weekend.
Kylie Ann Evans, understood to be Ched's sister, had written on Twitter: "Let's all get behind the Blades today and support Ched, 9th and 35 minute applause." She signed it with the hash-tag #justiceforched.
In the event, their attempts are reported to have "fallen flat".
Sheffield United defender Connor Brown has already been suspended by the club for comments he made on Twitter following team-mate Ched Evans's jail sentence for rape.
North Wales Police have arrested three people and are conducting an investigation after the victim of the rape was named and subjected to abuse on Twitter and other websites.
Her name was also accidentally published on Sky News, after they failed to redact it while reporting on the Twitter row.
