"The accusation that these young Muslims have sworn allegiance and obedience to the Islamic State is based on assumptions," lawyer Sebastiao Assurreira told AFP.
Arrested in December, they were charged in April with creating a radical movement as well as pledging loyalty to IS.
Two women arrested at the same time were later bailed.
Prosecutors say the men were preparing an attack and using face-to-face meetings and social media to radicalise others.
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"Our goal was to preach and spread the Islamic faith without inciting violence. We had a Facebook group of 1,500 members to discuss Islam," Ahmed Nladu Jose told AFP from his prison cell.
Angola, where 90 per cent of people identify as Christian, is not thought to have suffered a jihadist attack.
Seen by AFP, the charge sheet claims that information obtained from the suspects' computers, phones and books suggested "radical tendencies".
Under Angolan law, they could face between five and 15 years behind bars if convicted of creating a "terrorist organisation" -- and between three and 12 years for belonging to a terrorist organisation.
"It is quite normal that they talk about Islam on social networks, they have no weapons and have never been in Syria or Iraq," he said.
"They read and sold books on Islam. I have the right to read Machiavelli and not to apply his principles."
No date has been set for their trial.
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