Matthew Warren, 27, fatally shot himself April 5 at his home in Orange County by using an unregistered gun that he bought on the Internet.
"The day that I had feared might happen one day, since he had been born, and the day that I had prayed would never happen … happened," Warren told CNN's Piers Morgan.
Warren appeared on the show with his wife, Kay. They founded Saddleback Church in 1980 in Orange County, and Warren also wrote the best-selling book, "The Purpose Driven Life."
Rick Warren told Morgan that Matthew Warren struggled with borderline personality disorder and deep depression for much of his life.
"Matthew was not afraid to die. He was afraid of pain," Rick Warren said. "I remember 10 years ago, when he was 17, he came to me sobbing.
"He said, 'Daddy, it's really clear, I'm not going to get any better. You know, we've gone to the best doctors, the best hospitals, the best treatment therapists. Everything ... prayer, everything you could imagine ... good support.' And he says, 'it's real clear I'm not going to get any better, so why can't I just die?'"
Rick Warren shared his response:
"I said, 'Matthew, the reason why, is there is a purpose, even in our pain. And I am not willing to just give up and say that the solution isn't there. You might give up, but as your father, as your mother, we're not ever giving up, that we won't find the solution.'"
Matthew Warren was so desperate to get a gun to end his life, he went so far as to ask his mother for help, Kay Warren said.
"He told me everything. And he told me that he had found somebody, finally, on the Internet, who would sell it to him. And it had to be super encrypted, and it had to be, you know, this whole process ... he begged me to help him, because he couldn't figure out the process," she said.
"Here's my son in terrible pain, begging me to help him get a means to end his pain." she continued. "And it's like my son, I can't do that. I can't ... I can help you live. I will do anything to help you live. I cannot help you take your life."
Rick Warren said had Matthew Warren lived, he could have been "a great advocate for children in the world. He was an amazingly compassionate kid."