There are two different parts of "blogging"; the writing part and the reading part.
Why do I write a blog? I write because I love to write! Some of what is here I've written for classes, some I've written to clarify things in my own mind. Other things I've written because I truly believe that what I have to say is important and I don't read it "out there" enough. There are many false teachings out there and so many people just don't seem to care.
Why do I read blogs? I read other people's blogs for a variety of reasons. Some I read because I agree with them, others I read because I don't agree with them! Some I don't agree with, but I appreciate the author's consistent stand on a particular issue. (Note: I thrive on learning and find I learn best when my understandings are challenged. This is why I invite debate on my blog, but rarely get into debates in other places - unless that blog either also invites debate or I'm on the "side" of the blog owner; sometimes I do "break the rule" if it's an important enough topic to me.)
Why do I like blogs? I like blogs because the variety is amazing! There are so many different views of so many things and so many people blog for so many different reasons!
(SIDENOTE: one of my "must read every day" blogs is "Alicia Youngji Delgado". I've been checking on this very tiny little girl daily for most of her life! She's planning on going home today!
Why do I read the blogs that I read? Mostly, because I love God and the study of God: theology! Iron sharpens iron and Christians sharpen each other. I am encouraged, challenged and uplifted by the blogs that I read. Sometimes I'm discouraged, either at the shape of the world, the shape of the church, or the shape of me...
What encourages me? Comments (especially when I post photos of my kids). Interactions on the blogs of other Christians.
What do I do to encourage others? If I know that new(er) blogger isn't getting many comments, I really try to comment and just let them know that I'm reading and enjoying.
In the end, I blog because I like blogging. My kids sort of get into it also. They don't write here, although they could. But I started doing the photo scavenger hunt and they started pointing stuff out to me, "Take a picture of that!"
And the group blog I'm on: we were driving down the highway (well, my son was driving) and all of a sudden he slowed down. He pointed and said, "take a picture of that."