You should agree with him and tell him that, yes, that does seem to be what the Bible teaches - everyone can be a faithful and discrete slave if they act accordingly. But warn him that JW's will try to convince you otherwise.
You need to get a good book on JW's for him. I'm not sure of the Best one to suggest (maybe someone else can), BUT get someting you and he can reference. I recommend one that does not argue from an alternate religious viewpoint. Just somethin nuetral that uncovers all of their predictions, whacky teachings and destructive family policies.
This is very serious. If your husband becomes a JW it WILL mean bad things for your marriage, family and friends. Do not be complacent, do your research. Make sure you accompany your husband on any Bible studies he has with them. Ask the tough questions. Bring a JW expose' book so you have references on hand.
Here are a couple of Doosies you can ask:
Is it true that the Watchtower Society disfellowshipped people who spoke out against fellow JW's who had molested them? (there are numerous reputable News articles and reports detailing this)
How many times did the Watchtower predict the End of the world would come on a certain date? (try to get a number out of them. They will try to imply "never", but then show your hubby just how many times they did).
Do JW's feel that everyone else will be killed by God at Armageddon? (they will try to say "no" or "Only God knows for sure". Then you show your husband what they actually teach from their own literature.)
Just ask the tough questions and let them hang themselves with their own answers. You don't have to refute them right there and then. Just look up the info when it's just you two. Stay active on this board, thee are alot of smart people who can answer just about any question you have about them.
Whatever you do, work hard not to alienate yourself from your husband in any way. Try not to make it seem like a competition or battle of opinions. Remember you two are in this together. Don't let them do anything apart from the both of you. If you start asking the tough questions they will try to convince him, apart from you. He needs you, but just doesn't know it.