Mia Ayliffe-Chung, 20, was attacked at the Shelley’s Backpackers accommodation in the Home Hill area of Queensland in August.
Smail Ayad, 29, is alleged to have killed Miss Ayliffe-Chung, from Wirksworth, Derbyshire, and to have caused the injuries that led to the death of another Briton, 30-year-old Thomas Jackson.
The service at St Mary’s Church in Wirksworth featured readings from the Bible and Koran, as well as a Buddhist chant.
Giving the eulogy, Ms Ayliffe-Chung’s mother Rosie Ayliffe said her daughter had a “gentle, loving soul”.
She said: “I know the way Mia was taken from us has caused shock, not just in our small community - and what a blessing just now we have each other - but much further afield and across the world.
“Mia’s friends in Australia are doing as we are: trying to find ways to make sense of her loss and to give comfort to each other.
“We have to remember the extraordinary bravery of Tom Jackson in trying to save Mia, a bravery from which we should take great comfort in this hour of darkness.
“Tom barely knew Mia and yet he paid the ultimate price to try to save her.”
She continued: “Let his image be seared into your mind’s eye and overcome the uglier ones you have inadvertently been exposed to.
“Know this: there is no religion on God’s earth that would instigate a brutal, senseless act against an innocent young girl.”
Canon David Truby told the service: “What all of us really would have preferred would be for Mia to still be with us, still exploring Australia in the way that she was, still making friends and simply enjoying life.
“Sadly that was not to be. Her life was taken from her in a few moments of crazed violence, and not just hers but Tom Jackson’s too.”
The service booklet included thanks to Mr Jackson, who died in Townsville Hospital a week after he was critically injured as he tried to shield Ms Ayliffe-Chung.
It said: “Our thanks go to Tom Jackson for being there for Mia, and his family for being here for us.”