Walking into Sydney’s Lindt Cafe it’s hard to imagine the scenes of terror and violence that took place two years ago.

Bright Christmas decorations and jazzy music surrounded chattering customers on Thursday, while friends and loved ones gathered just a few hundred metres away at St Stephen’s Uniting Church to remember the victims of the cafe siege.

Sydney siege victims Katrina Dawson (left) and Tori Johnson.

Families of Katrina Dawson and Tori Johnson attended the public memorial service, while Prime Minister Malcolm Turnbull and NSW Premier Mike Baird gave scripture readings.

Two years have passed since gunman Man Haron Monis took 18 hostages, wielding a sawn-off shotgun and a backpack sprouting wires while proclaiming allegiance to Islamic State.

For 17 excruciating hours, snipers trained their weapons on the Martin Place cafe and tactical officers stood ready to pounce as negotiators tried in vain to make direct contact with the gunman.

It wasn’t until Monis, who was out on bail for violent and sexual crimes, executed cafe manager Mr Johnson that police were forced to launch an assault.

Officers stormed inside the building and killed Monis in a hail of bullets shortly after 2am on December 16, 2014.

Ms Dawson, a barrister and mother-of-three, was killed by police bullet fragments as she hid under a chair during the bloody shootout.

St Stephen’s was a scene of sombre joy and loving remembrance on Thursday, the church peppered with bright bouquets brought by those touched by the tragedy.

Sunflowers were prominent, a tribute to Mr Johnson, whose coffin was decorated with his favourite flower.

Ken Johnson, the father of Tori Johnson who was killed in the siege, attended the service. Photo: AAP

Reverend Dr Stephen Robinson referenced the sea of flowers that blanketed Martin Place following the siege as a symbol of solidarity for all Sydney.

“The flowers themselves were a very powerful symbol of the heart of people in the heart of the city,” he said on Thursday.

Attendees were then invited to lay flowers and light candles at the front of the church in memory of those lost.

Mr Baird said the second anniversary was a day to remember the terrible loss and violent deaths, as well as the tolerance and compassion that flowed in the days afterward.

-AAP