Some years back when I was big on Christian evangelism, there were a series of questions I had been taught to ask a person to see if they were "saved" or not. If not, I would go into various Bible verses that explained how they could be redeemed and so forth. I don't recall what all the questions were exactly, but I remember the last question went something like "if you were wrong, would you want to know?"
I think there's something telling about that question in regards to how spiritual conversations are often engaged. The attitude behind the question is, "if you do not have the same general beliefs that I do, then you are simply wrong and need to be corrected." At least, that was definitely my attitude then and it honestly took several years for me to shed it (assuming I even have completely). I think that attitude, though, is the reason why little to no real discussion happens between people of differing beliefs. One or more parties are only interested in dispensing what they deem to be truth and if others in the discussion dare to doubt that truth, they are written off and their ideas dismissed. "Agree with the Truth or just go away" seems to be the motto of many today.
A few such interactions is all one needs to find reason to never discuss their beliefs with anyone of differing beliefs ever again and hence many people stop talking about it, if they indeed ever started. I sometimes find it amazing that I haven't got to that point yet; my desire to discuss things regarding spirituality never seems to totally dissipate for one reason or another. However, I often wonder what is the best way to go about such discussions? How can we avoid detrimental or frustrating conversations of spiritual nature?
Perhaps it's best to first ask "what is the purpose of such discussions?" Back in my evangelical Christian days, I thought the purpose was to get people to believe like me so that they wouldn't go to Hell. Now, I think the purpose is simply to foster understanding and provide the opportunity for people to actually compare and weigh differing ideas instead of only bouncing the same ten tired ideas off of ten other people that essentially see things the same as you. If that is the purpose, it's only necessary to put the ideas out there and if people think it's far fetched, then so be it. There is no need for conversion.
Another thing we should consider is the effects of these discussions. Is what were discussing going to have a positive or negative effect on the person we are discussing with? I think this is relatively a hard thing to gauge simply because everyone is different and if you put something out online, you never really know who all will see it or how they'll react. Some people are able to entertain different spiritual ideas without necessarily accepting them and others simply cannot. For some people, to even suggest that something other than their particular belief could be true is to evoke immense anger or sorrow because our attachment to spiritual ideas (or lack there of) are just as much emotional as they are rational. So, I think we have to be cautious of giving ideas to people who clearly are not yet in a place to discuss them.
Lastly, I think we should strive for humility. We need to have the humility to accept that we, whoever we are, do not have all the answers and that people across the world and throughout time have been wrestling with the very same questions regarding spiritual truth and have come to different conclusions. So, we should view each discussion of such nature to be an opportunity not only to share but to grow and become familiar with all the various answers that are out there.