The Topeka, Kan., based church -- essentially the extended family of the church's founder, fundamentalist pastor Fred Phelps -- said Edwards is "going to hell" because she admitted to doubting her faith when her oldest son died in 1996, according to The Associated Press.
"God heard self-absorbed Elizabeth as she rode the talk show circuit spewing blasphemy," Westboro said in a statement.
"Elizabeth Edwards and her faithless husband, John, lightly esteemed what they had. They coveted things that were not theirs, and presumptuously thought they could control God," the church said.
In an interview with news radio 680 WPTF in Raleigh, Shirley Phelps-Rope, Fred Phelps' daughter, said she believes that God gave Edwards cancer as retribution.
"Of course that's what he did. And then he gave her a whoring husband. Don't you understand? You don't get to stomp your feet and flip off God and think that it's going to go well for you," Phelps-Rope said.
The Church's plan to picket the funeral has drawn huge counter- protest. As five Westboro members arrived this morning -- two adults and three children -- a crowd of 200-plus counter- protesters braved the raid and drowning out shouts from the Westboro clan, telling them to "go back to Kansas."
All of the protesting is taking place two blocks from the Edenton Street United Methodist Church.
Edwards was first diagnosed with cancer in 2004, just one day after the Kerry-Edwards ticket lost to George W. Bush in that year's presidential election. After grueling treatments she was declared cancer-free, but the disease returned in an incurable form in 2007. She died on Dec. 7 of liver failure.
John Edwards and her three children were among those at her side when she died, according to a family friend, who described the environment in the house as warm and peaceful and said the mood was sad, but also full of warm feelings at the time.
One day before losing her battle with cancer, Edwards wrote the following message to her fans and supporters on her Facebook page:
"You all know that I have been sustained throughout my life by three saving graces? My family, my friends, and a faith in the power of resilience and hope," she wrote. "These graces have carried me through difficult times and they have brought more joy to the good times than I ever could have imagined."
In recent years, Elizabeth authored two best-selling books -- "Saving Graces: Finding Solace and Strength from Friends and Strangers" and "Resilience: The New Afterword" -- and became a champion of causes involving poverty and cancer.
She is survived by three children -- 28-year-old Cate, 12-year-old Emma Claire and 10-year-old Jack.
During her eulogy, Cate Edwards shared a personal detail about her and her sibling's relationship with their mother.
"As some of you may know, Emma, Jack and I ended every conversation with our mom by saying 'I love you more,'" she said. "And she always responded by saying 'No, I love you more.' And as you can imagine, none of us ever won that battle.
"But today I have the honor of being the last to say: 'Mom I really, really love you more.'"
ABC News' Emily Friedman, Leezel Tanglao and The Associated Press contributed to this report.