The Freedom Party leader is standing trial after a court overruled a decision by the public prosecutor, who had argued Wilders was protected by the right to free speech.
Wilders is being charged over his 2008 film Fitna, which urged Muslims to tear out "hate-filled" passages from the Quran and juxtaposes images of the September 11, 2001 attacks on the US with quotations from the text.
He told the court on Wednesday that the trial showed that the right to freedom of speech was at risk in The Netherlands.
"I believe in my heart and soul that freedom in the Netherlands is being threatened," Wilders said.
"It is not only our right, but our obligation as free people to speak out against every ideology that restricts freedom."
In a five-minute speech to the court in which he also quoted Thomas Jefferson, author of the US Declaration of Independence, Wilders predicted future generations would ask how "we in 2010, in this place, in this room" defended freedom.
'Nothing against Muslims'
The release of Fitna prompted protests in Pakistan, Iran, Indonesia and Afghanistan, while Ban Ki-moon, the United Nations secretary-general, described the film as "offensively anti-Islamic".
Fitna is an Arabic word which has numerous meanings including "sedition" and "temptation", and appears in the Quran.
Wilders has previously sparked outrage over other anti-Islamic comments in the media, including calling for a ban on the Quran and comparing the book to Adolf Hitler's Mein Kampf.
However, in court on Wednesday, Wilders said that he did not have a problem with Muslims.
"I also do not intend to hurt people's feelings. I have nothing against Muslims," he said.
"I have a problem with Islam and the Islamisation of our country because Islam is diametrically opposed to freedom."
Constitutional right
Defence lawyers have argued that the court does not have the constitutional right to put the MP on trial, but the prosecutor said Wilders' remarks must be tested against the "existing legal framework".
If convicted, Wilders would face a maximum sentence of 15 months in jail.
Wilders supporters staged demonstrations outside the court, holding banners saying "Freedom Yes" and "Stop the Islamisation of Europe".
An anti-racism group has also responded to the trial by placing 100 comments from Wilders online to back up its allegations that the MP is guilty of inciting immigrant hate and discrimination.
Wilders has become one of the Netherland's leading politicians, with his party emerging last year as the country's second-largest party in the European Parliament.
Recent polls have also indicated the Freedom Party stands a chance to become the largest in the Dutch Parliament in national elections due in May 2011.
