It sounds like this person has vicariously incensed you to the point that you would like to physically cram his words back in his face. And though I would feel much the same way faced with that sort of prostheletizing, do take care to temper your actions if you are ever face to face with him! Hittin' the guy would only be a win for him and end up hurting you and your wife more. He is likely the type that would press charges and sue you into your grave. He doesn't sound worth THAT sort of anguish.
What sort of job does your wife hold? Is there a human resources solution? I agree that she should keep her responses to him short...."I feel harassed by you.....if you have an issue that relates to our job I would be happy to discuss that.......this topic is inappropriate at work......". She should avoid making eye contact and avoid him altogether if possible. He is obviously fueling his own fire and hoping others' will jump in his fire.....so far he is succeeding in a way.
My boss would try to draw me into discussions of religion and belief, so would his bro-in-law. Both of them knew that we differed deeply, they would have their spells where they couldn't let it drop. At first I tried to have tempered open, "agree to disagree", debate type interactions. That was a poor choice on my part. Eventually I learned. Whenever touchy topics came up, I put on my dumbest, doey-eyed, dead stare.....shook my head and shrugged my shoulders with an "I dunno" sort of brush off.....and thought of the first question pertaining to work or some unambiguous topic that interested him more. It usually distracted either one enough to forget about the original topic. When it didn't, I stuck to the dumb stare, even if it was uncomfortable to not say anything, and then excused myself to go back to work. Even when it was my boss (the owner of the small business)....along with the dumb look I would say "I'm gonna go and do, blah blah blah [whatever task I had previously been instructed to]". I recently decided to leave that position after 7 years. Though it sounds like your wife's harrasser is worse than what I dealt with on occassion, by far.
I hope she finds an effective solution and can get some peace!
