How can I forgive a God I no longer believe in? I have a lot of anger toward this non-existent deity.
It seems to me that you do, in fact, believe in God and this is hidden from you right now. Why do I say this? You cannot have anger toward a person who does not exist. How can a person who does not exist be unfair to you and therefore hurt you? It is similar with God. How can you have “a lot of anger” for a deity when you claim the deity does not exist? Your emotions suggest to me that you do see God as real. If this is true, then you need to ask questions such as this: Is God perfect, all holy? If so, then God cannot be unjust to you. Perhaps it is people who have hurt you and you are passing this now to God (“God should have prevented this,” as one example). If this is your mode of thinking, then I recommend a deeper dive into theology so that you can address the issue of why God allows suffering in this world; why God allows others to be unfair to you. In other words, it may be the rigors of this world and hurtful people at whom you are angry.