The first person to be prosecuted under France's year-old law against homophobic speech is a member of Parliament.
Christian Vanneste, a member of the ruling UMP party, faces jail and a fine after being convicted this week.
Vanneste made a series of anti-gay speeches in Parliament. In one he called gays a "threat to humanity".
His speeches, in the lower house, are protected by parliamentary privilege but Vanneste then repeated the remarks in interviews with two newspapers which printed them.
The charge was laid by the public prosecutor in Lille laid the charge following complaints by three LGBT rights groups.
Act Up-Paris, OS Homophobie, and Sneg - an LGBT business association, called the remarks repugnant and said they could lead to physical attacks on gays.
The UMP party has distanced itself from Vanneste, 58, a professor of philosophy.
He does not deny making the remarks to the papers but says they were far from being illegal. Vanneste says that he did not say homosexuality was dangerous "only that it is inferior to heterosexuality and could, in extreme circumstances, become a danger to mankind."
The prosecutor said Vanneste was guilty as charged but made no recommendation on sentencing. Judgment will be handed down on Jan 24.
He could be fined $25,000 or sentenced to six months in jail or both.