"When Your Honour looks at the various research reports produced by Family First, Your Honour will see that virtually all of those reports deal with matters that are of concern to all kinds of families, whether a solo parent, whether blended, whether so-called gay families.
"All of them are concerned with issues of youth alcohol, all of them are concerned with issues of screen time, questions of child poverty and child abuse.
"These are relevant to all kinds of family, although the research indicates some are more vulnerable than others."
Justice Simon France questioned whether Family First's research was "persuasion under the guise of research", where the authors of research papers chose evidence to reflect the views they already held.
McKenzie said that their research aimed to benefit everyone, and promote debate.
But although Family First admits to promoting "traditional" values, it was not a religious organisation.
"This is not a charity formed for religious purposes," McKenzie said.
"It is simply formed with a statement of purpose relating to faith, but it is not religious in purpose."
The Charities Registration Board made its decision public in August, to deregister Family First for the second time.
It had previously attempted to deregister the group in 2013, saying it did not "advance exclusively charitable purposes".
But the High Court ordered the Board to take a second look at the issue in 2015, after Greenpeace took the issue all the way to the Supreme Court, to defend its own charitable status.
In August 2017 the Board once again decided Family First should be deregistered as a charity.
"The board considers that Family First has a purpose to promote its own particular views about marriage and the traditional family that cannot be determined to be for the public benefit in a way previously accepted as charitable.
"Family First has the freedom to continue to communicate its views and influence policy and legislation but the board has found that Family First's pursuit of those activities do not qualify as being for the public benefit in a charitable sense."
The Charities Board has not yet made its submissions to the High Court. The hearing continues.