I was asked this recently.
An answer is harder to come up with than you might assume. If you look back to my first few posts around New Years 2010 you don't really come up with a solid explanation. Why would one blog? is not the same question as Why does Colin blog? You can dress yourself up as much as you like, but you are still the same weirdo under the clothes.
1. I like blogging. I like writing. I like thinking. Why? Take it up with God.
2. I like sharing in this way about my Faith and my family life. Why? Thomas et alia say that the good is diffusive: it flows outward,by nature it likes to share and be shared. My family and Faith are good so they urge diffusion. But why do I like to share about them, because some people are hesitant to do so? I like being able to control the flow of information. I can talk about what I feel is safe to talk about, and not what I don't feel is. I consider myself an introvert, and blogging is a relaxed activity I can do on my own time, quietly.
3. It's evangelical. Giving witness to the graces in my life. Sharing the truth about Jesus Christ and His Holy Church. Pointing out evil when I see it, in a way that is constructive.
4. In the movie, Shadowlands, C.S. Lewis is made to say, "We read to know we are not alone." I'm no Lewis scholar, so I don't know if he actually said that, but I like it. I suppose I write to know I am not alone. I seek some sort of faith and intellectual community, I guess. I think about this aspect of St. Augustine, who seemed to be so much in search of sympathetic souls.
5. I try to fill a void. People are bored and looking for good things to read online. I try to be interesting, and serve the need to hear good and interesting things that all people have.
6. Now with the Society of Canadian Catholic Bloggers I try to facilitate growth in community, strength, direction, hope, inspiration, and knowledge among Canadian Catholics.