He got very confused to say the least, asked where I think we should worship and some other questions, the answers to which I honestly confessed that I do not know.
This issue is a huge hurdle for JWs, or anyone else in a religious cult for that matter. In a cult, salvation is dependent on association with the group, therefore anything wrong with the leader/doctrine has to be reasoned away. Because, where else will we go? Point out that the Bible is referring to Jesus, not an organization.
You've made great progress. If he brings up this issue again, emphasis that you are not advocating that you guys need to run out and join a man-made group. Look to the scriptures, live a good life, treat others will love and respect. Is that not enough for Jehovah? If your husband asks about "who else is preaching", ask him if it's important that truth be taught, or if salvation is simply dependent on the ritualistic behavior of going door-to-door?
You would have to tread very carefully, but you can also ask him if it matters to Jehovah that JWs have gone door-to-door teaching falsehoods? Is it important to teach truth, or to simply teach?
I just talked to a JW, and she claimed Jehovah has always had an organization. So I politely asked her which organization Jehovah was using in the 1800s? She gave me a deer in the headlights look, and then changed her tune and said that Jehovah has always used individuals. You need to really impress on your husband that you're worried that by following imperfect men (The Governing Body), or an Earthly, man-made organization you might put yourselves into a position of being led away from the truth of the Bible.
Ask him if it's more important to be obedient to the organization or the scriptures? Some of my JW relatives refuse to even answer this question, because their mind simply doesn't want to go there. But just bringing it up might get them thinking about it. They can't acknowledge that there could ever be a discrepancy in the two, because they've essential been taught that the Organization=Jehovah.
I almost forgot, you shouldn't really be "telling" him anything. Ask him questions, make him explain it. You can't do the thinking for him.
Ask him to explain John 6:68. When he drifts into the Watchtower explanation, kindly point out that you don't want to go beyond the things written, that you feel there's danger in being led away from Bible truth by doing that.
Open the Bible Teach book to pg. 183, and have him explain what baptism signifies. It specifically says that baptism is to Jehovah God alone, not to an organization. Have him explain the discrepancy, ask him if he thinks that paragraph would be misleading to interested ones.