Keeping a journal serves many purposes. It is a place of reflection in the moment. It is a way to “get things off your chest” where they can fester. It is a way to open a channel with your soul and take a step away from the ego. It is a place to open a channel to God and create a new way of praying. It is a way to be more self aware.
You do not need to be a writer to journal. You do not need to have a relationship with God to open a blank page and start one. You can throw out each page after you write it if you are not ready to deal with your own shameful or guilty thoughts once you see them in print. But it is my experience that no change can begin without real honesty, and sometimes the only place we can explore real and raw honesty is alone with a pen and paper.