All you need is someone with a Master's Degree and you monitor the online work. Its all done on the internet now as they measure the time you spend on each subject. Use the Beard with the MA to sign off on the work and supervise the testing, but you can also take him down to where the tests are being given, usually the local Community College or nearby Uni. They have to take a test for each subject, each semester. I may be over simplifying it, but not by much. I lived in Las Vegas for a time and they have the worst education in the country with only AZ beating them out for dead last. A lot of kids are home schooled there and its not hard.

Nothing specific but check out secular schools that offer correspondent courses with skype.

We had the same problem with my grandson. We just send him to a religious school and then I deprogram him after. He sits down with his grandad and we have a laugh together at their silly ideas. But he's not allowed to tell any of them that he has this secret knowledge. We have a great laugh together at their expense

[time4learning.com] [freereadingprogram.com],[discoveryk12.com], [xtramath.org], [prodigygame.com], [mobymax.com]

What do you mean 'need help finding an athiest home'? What are you?

This FB forum might have some resources.
[facebook.com]

Good home schooling has the advantage of allowing the child to progress at their own speed. This is especially helpful for a gifted child because they don't get bored. Children need socialization as well. Many locations have organizations that bring home school children together for group activities such as soccer or museum visits. I hope yout grandchild will participate in these opportunities as well. I have a grandchild that was home schooled for religious reasons and she was afraid of her shadow on a public playground which broke my heart.

Khan Academy.

. . . hmm, I wasn't aware that "home schools" taught students other-than their own children.

Do a web search for secular schools in your area.