Lack of Comments

A handful of people from my community (church) are bloggers. Oftentimes, they have wonderful posts that I would expect to spark a great conversation.
In person, I am sure conversation would ensue.

But on the blogs, comments are sparse.

I wouldn't see this as a problem if I thought that only 2 or 3 people were reading the blogs. But I know there are more.

So, what are the reasons that more people don't comment more often?
Would having a community (church) blog help?

I'd like to have an international community/audience on our blogs. But I'd rather keep a local focus.

Maybe having a common blog would make posting comments more comfortable?

If people disagree with a post of mine, I'd rather they comment and we discuss, than they hold back.
It's just not fun to post something you consider is deep or meaningful, and nobody comments.

Maybe more people would do this on a community blog.

Maybe a blog that was a combination of Blog, IRC, and Instant Messaging:

• The post/comment format of a blog.
  
• The community prescence of IRC, but not the short message entry length, or disorganization of cross talk.
  
• The quick response of IM notification when there is a new post.
  

Something that encourages deliberate, organized, low-latency conversation, with a communal feel that immerses you in conversation.