You don't need letters or words to convey your heart's worries or desires to God. He listens to your feelings and emotions, and even the inner turmoil that even you can't understand yourself. By 'God', I do not refer to a specific God (whether I capitalise it or not) or religion. I believe that God is an energy that exists on the foundation of faith in our hearts. We can call the energy God, Universe, Almighty, Creator, or any name you would like to give. All I know is that God does exist for me...since I have seen miracles, I've seen situations turn around in a blink just after I made a prayer about the same. God is all about believing.
Now, you would think about why I write letters to God when He can hear all my unsaid thoughts and feelings. Well, I write them to clear up my mind. When you're not clear about what you want, you won't get it. And writing is like therapy for me, to keep my mind free of clutter. When I write a letter to God, it makes me think about what is actually bothering me and if the thing I'm working about is truly worth the bother.
And other than writing about my wishes and worries, I frequently write 'thank-you' letters to God because gratitude is the best practice that you can cultivate. By thanking God for every good thing that happens to me, my heart feels the best; I feel humble because whenever I achieve a milestone present on the ladder of success, I hand over the achievement to God, it's His grace after all. It's hard to climb that ladder, easiest to fall off it, and I need God's hand to hold me up on each step I reach and to climb higher.
If you believe in the law of attraction and manifestation, writing letters to God/Universe is a great tool to manifest your heart's desire. But it won't work until you place your faith in God/Universe and detach from the result of manifestation. Even I feel scared at times because putting your trust in the unseen is not easy but when your endless prayers have been answered, you love putting your trust in that Divine Power.
To know more about how I started writing letters to God and how Poetic Letters To God came into existence, you'll have to read the book. It has all the answers in its introduction.