Riddell told RNZ it would be "irresponsible" of him not to take on a young client wanting to change their sexuality.
His website says Living Wisdom offers a "Christian friendly" methodology using "rational emotive and brief misbelief therapy approaches."
Riddell is not registered with the New Zealand Association of Counsellors or The New Zealand Christian Counsellors Association.
He said those who have chosen to live a same-sex lifestyle have only done so under severe emotional duress and says he utilises "misbelief therapy" to help clients unlearn certain behaviours.
"If a person who is a heavy drinker or grossly obese can take themselves to Alcoholics Anonymous or to WeightWatchers and seek help to successfully reconcile the discordant urges within, why can't the person conflicted with unwanted same sex attraction go to a counsellor and seek the same help?"
Riddell said that under New Zealand legislation this option has been removed.
"Alcoholics Anonymous and WeightWatchers are applauded by society, but to my mind their goals to help is not different from what any carefully-trained counsellor wants to offer the gender confused."
He said he foresees the day when the secretive self-loathing "these people" experience will lead to many suicides.
"Contrary to what the gay juggernaut would have you believe, not everyone who experiences same-sex attraction welcomes it.
"I have many clients who will attest to that, I do not seek these people out - they find me."
Riddell made a submission opposing the conversion therapy bill, saying he did not want to go to prison for his "humanitarian" work.
Race Relations Commissioner Meng Foon said the practice is a clear violation of human rights.
"There have been a number of cultural and religious practices in Aotearoa which are seemingly inhumane, contradict the Human Rights Act, the freedom of expression, of religious diversity and the freedom to be safe."
He said people continuing to offer conversion practices is a big concern.
"By strong persuasion some people would like to extinguish people's belief or how they feel."
Foon said if anyone was under duress or concerned about conversion practices they should be assured the law was on their side.
"It is very important that we uphold those rights of those individuals or groups to be who they want to be."
President of the NZ Association of Counsellors Christine Macfarlane said they have a clear stance of ethics and behaviour.
"It's harmful behaviour and I would encourage the whānau or anyone in the public who knows of this to make a complaint to the Health and Disabilities Commissioner, they will investigate and there will be consequences to this."
She said one of a counsellor's foundational values is to do no harm.
"We know and there is much research out there internationally that trying to change somebody in any way in regard to their cultural, gender or sexual identity is harmful."
Macfarlane said the negative effects of the practice are obvious.
"It leads to psychological distress, suicidality, mental health disorders. As counsellors we go into counselling to help and support and increase well-being, completely opposite to what conversion therapy does."
However, Riddell remains defiant.
"We won't be intimidated by the incensed threats of the leftist ideologues who display little ability in conducting a reasoned discussion, or demonstrate any compassion whatsoever for the abused, attachment-injured child as that child stumbles through the fraught journey of emotional formation, back to a newly repaired or re-awoken heterosexuality."
Police say any information received about alleged offences relating to this legislation will be assessed and investigated as appropriate.
WHERE TO GET HELP
If it is an emergency and you or someone else is at risk, call 111.
For counselling and support
Lifeline: Call 0800 543 354 or text 4357 (HELP)
Suicide Crisis Helpline: Call 0508 828 865 (0508 TAUTOKO)
Need to talk? Call or text 1737
Depression helpline: Call 0800 111 757 or text 4202
For children and young people
Youthline: Call 0800 376 633 or text 234
What's Up: Call 0800 942 8787 (11am to 11pm) or webchat (11am to 10.30pm)
All services are free and available 24/7 unless otherwise specified.
- RNZ