So i have a question about this, and contrary to what some may tell you im not trying to be rude, however the question is relevant:
why?
Why is the only question that matters, and on several fronts...
For one thing, having an end result in mind makes it easier to establish a plan to get here. So whats your goal...? Is it to warn him away from the jw’s? Is it teach him christianity? His mother is atheist and his father sounds like he is non practicing of any specific faith as are you and your husband, so why teach him any christianity?
If its to warn him away from the jw’s why do you need to teach him christianity to do that? There are other just as effective ways and those methods could apply to a lot of high control groups or cults, not just jw’s.
Also, why is this your job? He has a mother and a father. That sounds like their job. His mother (as noted earlier) is an atheist, does she want this basic christian education? Does his father? Have they talked about it between themselves as his parents?
Theres a few more questions but in the end, not to put too fine a point on it, why does this fall to you?