When I was in a bad spiritual state, I struggled a lot with self-condemnation and unbelief, and it was not pleasing to God at all! Faith is actually one of the weapons of a born again Christian to overcome sin. As you are fighting against sin by fasting and prayer, you should also have faith. Believe that you will be free; believe that Jesus is powerful and He is going to deliver you in His right timing! I promise you He will!
When those thoughts come of, “you won’t change, God won’t help you, it’s always going to be like this,” tell satan directly: “That’s a lie! I recognize your devices, and I refuse that in Jesus Name! I know you are trying to discourage me but you will always fail in your attempts to defeat me.” Also praying in scripture out loud will give you power and help you to overcome those discouraging thoughts. Remember that when Jesus was tempted by satan in the wilderness Jesus responded with the Word of God (Matthew 4:2-11).
-Jolie Josephine Harris
Hebrews 11:6 King James Version
But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him.
Ephesians 6:16 King James Version
Above all, taking the shield of faith, wherewith ye shall be able to quench all the fiery darts of the wicked