I write for the 2nd and 3rd reasons. As I write mainly fiction and poetry I always place a message within those stories. It may be a more subtle approach than writing articles that challenge them directly, but I think I am very effective at getting my message across or teaching a life lesson. People don't feel as confronted, and I feel if there is a message in something they enjoy reading they are more likely to remember and implement it.
I am confident I have the writing ability to change people's attitudes and lives through my creative writing. Thank you for making one think, and for opening a healthy debate, Nour.