Phil and Willie Jones bought the billboard in an attempt to reach their adult son and daughter, Mike Jones, 42, and Emily Jones, 38. Phil said his children work for the church in Los Angeles and have been prohibited from speaking with their parents.
Phil told BuzzFeed News that for years, the entire family participated in Scientology. But eventually, he and Willie began drifting away, finally severing ties with the religion four or five years ago. When that happened, they were cut off from their friends, family, and children who stayed with the church.
"We knew that in Scientology, if you speak out all your family and friends have to disconnect from you," he said.
It has been years since the family was all together.
Phil said it has been three or four years since he has seen Mike and Emily. A few months ago he had a brief phone conversation with Mike, who, according to Phil, ended the conversation by saying, "I never want to talk to you again." Phil added that Emily got married last year, but "we weren't invited, we weren't told. I only found out through the grapevine."
"They've been poisoned against us, they've been convinced that we are evil and trying to destroy the world," Phil added. "They've been worked on and there's definitely a mental conditioning."
Representatives for Scientology did not immediately respond to BuzzFeed News' request for comment Wednesday.
The Jones family has tried to reach their children in the past using missing person signs and notes passed along by friends.
Phil said he posted flyers asking if people had seen Mike. Earlier this year, he also asked a friend to pass a note to Emily while she was attending a Comic Con event in Salt Lake City. Phil didn't get a response from those efforts.
Phil believes Mike and Emily are being victimized, adding that he and his wife just want to stay in touch.
"We got them into this," Phil added. "We raised them in it and we do feel a responsibility having gotten them in."
The couple paid for the billboard with a GoFundMe page, which Phil said received overwhelming support from other former Scientologists.
The initial plan for the billboard was for it to focus on the Jones family, Phil said. But as they tried to raise funds, they had an overwhelming response from people sharing similar experiences.
As a result, they broadened the scope.
"To my loved one in Scientology," the billboard reads, "call me."