Peter Tatchell has welcomed a High Court ruling in favour of a Christian worker who was demoted for a comment he wrote on Facebook about equal marriage.

In a statement, the human rights campaigner said:

“This is a victory for free speech and fair play. Although Adrian Smith opposed religious same-sex marriages, he supported the right of gay couples to get married in a civil ceremony in a register office.

“He is entitled to his view and should never have been demoted. I am glad that my statement in support of Adrian was used in his legal case and that he has been vindicated.”

Mr Smith lost his managerial position and had his salary cut by 40% by Manchester’s Trafford Housing Trust after he commented in an online news discussion about gay couples marrying in churches by saying it was “an equality too far” in February 2011.

On Friday, the 55-year-old won a breach of contract case against Trafford Housing Trust at the High Court in London.

Mr Smith’s damages payout was limited to £100 because of legal technicalities.

He said: “I didn’t do this for the money – I did this because there is an important principle at stake.”

In a statement, Mr Smith also criticised the government’s desire to introduce marriage rights for gay couples and said:

“I have won today. But what will tomorrow bring?

“I am fearful that, if marriage is redefined, there will be more cases like mine – and if the law of marriage changes people like me may not win in court.”

He added: “Does the prime minister want to create a society where people like me, people who believe in traditional marriage, are treated as outcasts?”

The Christian Institute, the anti-gay group that paid for Mr Smith’s legal case, welcomed the ruling.

According to Sky News, spokesman Mike Judge said: “This is a good day for free speech. But would Adrian have won his case if marriage had already been redefined? I don’t think so.

“The government should stop playing politics with marriage, because it’s ordinary people like Adrian who’ll get it in the neck.”

Matthew Gardiner, chief executive at Trafford Housing Trust, said: “We fully accept the court’s decision and I have made a full and sincere apology to Adrian”.