Around 100 Muslim protesters calling for the jailing of Governor Basuki Tjahaja Purnama chanted "God is great" outside the court, while supporters of the ethnic Chinese Christian sang the national anthem.
A cordon of police stood guard outside the court after Muslims, led by hardliners, took to the streets in December and November, to call for Purnama's arrest and to urge voters not to re-elect him in February.
The rallies, with over 150,000 participants each, were the biggest Jakarta has seen in nearly two decades.
Purnama told the court he had not intended any insult during a trip to islands off Jakarta when he commented on opponents use of the Koran in political campaigning.
"It is clear what I said in the Thousand Islands was not intended to interpret the (Koran), let alone to insult Islam or the ulema," said Purnama, who was responding after the prosecutor read out the charges.
The governor said that his comments were targeted at rival politicians trying to get an unfair advantage in the election by saying that voters should not support a non-Muslim.
Purnama, who is running for re-election against two Muslim candidates, described a loving relationship with his adoptive Muslim parents on the remote Bangka island.
"I am very saddened that I have been accused of insulting Islam because this accusation is the same as saying that I am insulting my adoptive parents and siblings."
During the hearing, Purnama sounded typically defiant at times. Quoting from his book "Hiding behind holy verses", he said many in the country's political elite were "cowards" who sought to divide Indonesians to gain power.
Purnama, if found guilty, faces up to five years in prison. Almost all blasphemy cases in recent years have ended in conviction.
RELIGIOUS MINORITIES
Supporters of the governor, whose nickname is Ahok, were also outside the trial, which was aired live on television.
"He is absolutely suited to be governor," said Charles Simanjuntak, 46, who praised the development of the city under Purnama and said he did not believe the governor had committed blasphemy.
Among the protesters opposed to the governor, one group held a placard reading "Jailing Ahok = fair government"
President Joko Widodo, seen as an ally to Purnama, has blamed "political actors" for fuelling the protests, but declined to elaborate. Widodo has faced widespread criticism for not doing enough to protect the country's religious minorities.
Indonesia has the world's largest Muslim population, but the country of 250 million also has sizeable Christian, Hindu and Buddhist communities and dozens of groups that adhere to traditional beliefs.
As governor, Purnama won kudos for shaking up the city's sleepy bureaucracy and for taking steps to ease Jakarta's notorious traffic. But his abrasive language and insistence on clearing the city's slums has alienated many voters.
Recent opinion polls showed Purnama, once the frontrunner in the race to lead Jakarta, has now slipped to second place, behind Agus Yudhoyono, the son of former president Susilo Bambang Yudhoyono.
At the end of the first day of the trial Purnama appeared to be whisked away from the court in an armoured police truck. The trial will resume on Dec. 20.
