While the meal is free, it is a ticketed event, and many diners are referred through other agencies.
Ms Marriner, a Bay Leisure Events programme co-ordinator, said this is the second year she has been a Christmas dinner helper, having once been a dinner guest herself.
"It's a wicked event to be part of. Once again our volunteers, church members and local businesses have been awesome in donating cash, goods or services or just giving of their time to help out.'
"Every year we start with no money and everyone I have gone to has not turned us down.
But there is still time for people to donate food items or make a cash donation, and anything not used on the big day won't go to waste."
Ms Marriner said almost 80 volunteers are involved in making this year's event a success, which includes cooking and serving the meal, providing transport and wrapping presents.
This year the meal will be served in the church rather than the church foyer to enable a greater number of dinner guests to be fed.
A NZ Fire Service crew will be turning up on Christmas morning to help remove all the pews and set up all the tables and chairs on loan from Bay Leisure Events, she said.
There is also a Christmas gift for everyone who comes along, thanks to generous businesses such as Farmers and The Warehouse.
Those who attend the dinner come from all walks of life.
"From older people who may have suffered a recent bereavement of their partner, homeless people, and family groups," Mrs Marriner said.
"This year we have a number of bigger family groups coming. It's a real mix of people, a real slice of life from across the city."
"Some of the stories we hear from our dinner guests are quite heartfelt and very sad."
If anyone can donate supplies, or join the clean-up team call Ms Marriner on 027 963 5648.