I'd never heard of it, but found some links. You might want to dig for a forum where past family members or friends have the opportunity to vent and share stories.
Worldwide Church Of God--Modern Day Cult
Worldwide Church of God (WCG)
Worldwide Church of God - Christian or Cult?
THE CULT OF ARMSTRONGISM
Herbert W. Armstrong - Wikipedia, the free encyclopedia
In any cult, there will be a good percentage of people who honestly believed they were doing something good for the world or for God. Sometimes too much, driven by proving their worth.
104 splinter organizations... wow a lot of semi-dissatisfied members!
It looks like it had a Holiness slant -- lots of personal restrictions. That intensity of self-discipline can sometimes cause people to compete, push each other down, teach salvation by self-righteousness rather than God's righteousness and grace.
I have found that any organization is multi-faceted, and can look different from every angle inside and outside of it. Older denominations are like standard-cut gems, sometimes boring but reliable; where newly-launched revivals are lopsided conglomerates of whatever happened quickly. They look different from every angle because they are still forming and morphing.
Jesus taught about the seed that falls on good ground and bad. An experienced farmer knows to take out rocks every spring before planting, to fertilize and water and plan for sun.
An inexperienced farmer in a hurry for growth might throw a handful of seeds in a mud puddle, exclaim success when the seeds pop up, neglect the continued growth. And then teach that all farmers need is a mud puddle and a handful of seeds.
I hope you find out more -- sometimes precious information is in small spots at the end of the search engine results.