Is it a blasphemous thought to think that you hate God? Of course not! In fact, go tell God what you are thinking. He wants to hear it. Seriously. The last thing God wants is for us to shut ourselves off from Him. So if we are having blasphemous thoughts toward God, the best thing we can do is talk to God about them, so that He can show us how much He loves us, and how the God we think we hate is not actually the God He truly is.
Scripture seems to indicate that repentance is necessary to receive the forgiveness of sins. A second look at repentance reveals otherwise. Repentance for the forgiveness of sins has nothing to do with gaining eternal life and entering heaven, but about freedom from the captivating and addictive power of sin.
Some people seem to believe that confession of sin is required for the forgiveness of sin, that you are not forgiven unless you confess. This idea comes from 1 John 1:9, but represents a misunderstanding of the context of 1 John, and the differences between a relationship with God and fellowship with God.