I'm sorry to hear of your loss. I hope the Lord abides with you and your loved ones during this time of difficulty.
The truth behind that system goes well beyond the link you've shared. It provides a loose overview with references to practices most never undertake and their knowledge is limited at best. To understand the crux of New Thought you'd need to understand its roots. And most who reference that message don't mention The Secret or its offshoots. They're minor gateways to something larger.
It's a lot like the musings on the Illuminati. Many reference symbols and behaviors which suggest its presence but can't provide anything beyond speculation. They've never gone down the rabbit hole and are speaking from a position of books and Internet searches.
Reading about a subject doesn't make you a practitioner no more than watching The Food Network would make one a chef. Experience is the difference. Millions of people have read Hill's book and used it as a motivational tool and nothing more. Much like some people read the bible and others are compelled to dig deeper.
The journey is a choice. I think it's best to limit our reference to motivational speaking. I would never make a charge of something more without definitive proof. To suggest a minister has crossed into the systems you've mentioned is a serious charge and it isn't an accusation I'd make in your place.