“This isn’t ‘straight pride’. This is hate pride,” said Matthew Mason.
The National Straight Pride Coalition (NSPC) refers to the parade as one of its “war events”.
The organisation states that its purpose is to “defend” children from “the inherent malevolence of the homosexual movement towards our founding principles".
“This is the woman who raised me actively working against my rights as a human being, who I am as a person,” Mr Mason said.
“I am afraid of violence happening. I don’t want anyone in my community to be hurt.”
“It is again white Caucasians who did come to this country to start liberty and gave us the greatest Constitution in the world,” Mylinda Mason said.
Mr Mason appeared before Modesto’s city council on Wednesday to formally oppose the right-wing group’s request for a parade permit.
He also organised a vigil to demonstrate against the event.
More than 100 people protested against the parade outside Modesto’s town hall during Wednesday’s council meeting.
Don Grundmann, the NSPC’s founder, criticised Mr Mason during proceedings, which became heated.
“I want to thank Mr Mathew Mason for organising a candlelight vigil against our event because it shows you exactly what we’re dealing with,” said Mr Grundmann, according to CBS local.
“A one way street for tolerance in this nation.”
The audience booed him, leading Mr Grundmann to engage in a shouting match with some members.
The council will decide whether or not to issue a permit at the end of the week.
Mr Mason denounced both his mother and Mr Grundmann during Wednesday’s meeting, claiming he had "personally heard" his mother "use hateful, harmful rhetoric when describing the LGBTQ+ community and non-Christian religious communities, according to SFGate.
The 28-year-old said he was estranged from his mother because he was gay.
“This is not a positive message and this community is committed to positivity, to love, to inclusion and to diversity,” he said of the NSPC’s beliefs.
“And this message is none of that.”