This very much summarizes what I believe on journaling...
"I was very cautious about what I put in the journals. I don't think it was because I feared someone else would discover my secrets. I think I was afraid to articulate, even for myself, feelings I might have to get rid of. Better to stick with what God was saying to me than what my heart was saying. It seemed the safer course. I do not repudiate it now. The only way to build a house on the rock is to hear the Word (I couldn't have heard it if all I listened to was my feelings) and then to try to do it..."
Elisabet Elliot, Passion and Purity (p. 54)
Nancy Wilson also wrote a while ago two posts on journal-keeping that are worth considering:
Part One. Part Two (if you only have time to read one, read part two. It is excellent -a must I would dare to say-.
"[W]e should and must guard our tongues in all things spoken and written: “He who guards his mouth preserves his life” (Prov. 13:3). Psalm141:3: “Set a guard, O Lord, over my mouth; Keep watch over the door of my lips.” Our pens need watchmen and guards just like our mouths. And the fact that a journal is “private”does not mean the words can be left unguarded." -Nancy Wilson
"Life is short. Write good words." -Nancy Wilson