I can not believe that God will be merciful to me.
That is almost too difficult for a person to believe. Your heart cannot comprehend that, that is how we are. When Christ offers Himself and forgiveness of sins to us, we run in the opposite direction.
As a little boy I once went singing with a friend to collect sausages. Then someone came along who shouted for fun: ‘Hey, what are you doing, scoundrels! I will make sure you won’t like it!’ He came with two sausages for us. But we ran away, while the man only wanted to give us something. This is exactly the same as it is with God. We flee from Him, and yet He only wants to give us something good.