I think you must understand as well that if he recently went back to the org or has recently been to an assembly or convention he will be in high dub mode for awhile. Carry on as usual and try your best to minimize the cult effects. Meaning, ignore his super dubness for now, it will fade in short bit. They seem to go in cycles according to whatever the recent message is. You can actually determine ahead of time just where your jw is emotionally and 'spiritually' by what they are studying at any given moment. It seems to go on a yearly recycle (in my mind anyway) and some months I dread because I know this will be a doom and gloom month or a very judgmental month, or time to be a hardass 'they deserve it ' mentality. Unfortunately you will come to know this ahead of time if you research and keep somewhat up to date and sadly it becomes part of normal life.
If they are in super dub mode full of gloom and doom have ready some really uplifting human interest type stories! Stories of regular people helping others, being selfless and you will be cheerful and so full of love and hope at these stories that he will be disgusted and let the whole conversation drop. Back to what's for dinner if you must......
If you absolutely must have a conversation then use the scripture Romans 14:5- NIV -One person considers one day more sacred than another; another considers every day alike. Each of them should be fully convinced in their own mind.
Under no circumstance should you ever accept the NWT as an acceptable Bible translation. jw's will accept other translations but you must not accept their perverted version. I think they will, reluctantly, accept the King James if you are acceptable to that. My jw did accept Revised Standard Edition at one time. Who knows now though.It is very odd, we went through sheer hell (and that is being charitable) when he joined up and years later he seems able to separate his jw-ism and normal life. Like living 2 different lives sometimes. But, make no mistake jw-ism is always right under the skin of things, always. We often have conversations that we both know are jw related but never mention actual jw/religious things. It is a weird dance we have developed over the years and I do not recommend it for anybody. I still remember our pre jw relationship and still miss it to this day.
I just want to shake your jw and mine and say what the hell is wrong with you? wake up. That doesn't work, trust me on this one.
Wish I had a magic wand for you and all the rest of us with loved ones caught in this cult.
Hope springs eternal, maybe one day.