In his resignation letter, Terrence Lo says that as an Asian, atheist, and parent of a gay son, he can't in good conscience stay with the party.
"It's a very powerful minority that is shaping the culture of the party, unfortunately, that is not only LGBT unfriendly but also ethnic unfriendly as well," he said in an interview with Calgary radio station CFFR.
"I still don't believe it is a majority, but I do believe that there is an undercurrent there that is actually very much pro-lake-of-fire."
Party members on the weekend voted against adopting as policy a statement supported by Leader Danielle Smith that affirmed the rights of everyone regardless of race, religion, sexual orientation and other differences.
The expanded definition had been held up by the party for a year as the shining example of a new moderate centrism palatable to Albertans across the political spectrum.
Instead, members voted Saturday to go with a broader policy to recognize that "all Albertans have equal rights, privileges and responsibilities."
In the 2012 election, the party appeared to be on the road to winning when it was derailed by controversies that included comments by one of its candidates who, in a blog, had urged gays to repent or face an eternity in hell's "lake of fire."
Lo, who was vice-president of communications for Calgary-Glenmore, called the vote the breaking point for him.
"I had basically been pondering about all of this literally since then and pretty much by Monday night I realized that for me to stay was untenable," he said.
He added he doesn’t expect his resignation will precipitate a mass exodus of supporters, but hopes his decision to leave inspires others to pay attention to the party’s actions.
Smith said she was disappointed that the party has lost Lo's support, and will try to win him back.
"I would say that every political party has a range of different perspectives on controversial moral issues and I think that every political party has to grapple with how to deal with those in policy," she said.
"These issues are ones that people feel passionately and strongly about and there is obviously a strong reaction to what happened on the weekend, but I think that, through our actions, we are going to be able to demonstrate that we are continuing to broaden our base and attract more people to our party."
The vote Saturday happened while Smith was out of the room. She later suggested that members were concerned that a group may have been forgotten in the more specific policy so they voted for the broader policy instead.
She noted that her party has donated money and time to support events and causes in the gay community.
"I suspect that these issues are just going to keep coming back over and over again and so, as we continue to grow as a party, I am sure that we will find the right language so that everybody feels respected," she told reporters at the legislature Wednesday.
"It may be that we have to take another crack at it again in the future."
— With files from CFFR and CHQR
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