Worshippers Melvin Cravitz and Adrian Daulby were killed when Jihad Al-Shamie, 35, drove into the gates of the Heaton Park Hebrew Congregation Synagogue on 2 October.
Al-Shamie then began attacking with a knife, while wearing a fake suicide belt, before he was shot dead by police.
The attack took place on Yom Kippur, the holiest day of the year for Jews.
Cravitz, 66, died from multiple knife wounds inflicted by Al-Shamie, while Daulby, 53, was struck by a single gunshot wound to the chest fired by an armed police officer scrambled to the scene in Crumpsall.
Senior crown prosecutor Aamir Sajad said: “No one has the right to make other people feel like their life is at risk just for doing their job.
“Gabriel Levy gave no thought to who was at the other end of the phone when he recklessly called two mosques to make these terrifying threats.
“He claimed that he had no real intention of causing any harm – but this means nothing to those on the receiving end of these types of illegal and intimidating communications.
“Death threats in any form have a severe impact on those who receive them, and we are grateful to the victims in this case for coming forward.
“Today’s sentencing shows that threats to kill and Islamophobic hate crime will always be treated extremely seriously by the CPS and we will take swift and decisive action when seeking these convictions.”
