Why Hamlet delays killing Claudius?

In the Shakespearean play, Hamlet, the main character, Hamlet delays killing Claudius, his father's murderer, for a number of reasons. His main reason is his unsure mind about the ghost's apparition, then his pure mind of not sinning himself for killing him at prayer and lastly because he wants to catch Claudius at a time when he is killed, he has no chance of going to heaven.
As the opening of the play, Hamlet learns about his dead father's murder. Even though he shows anger and want of revenge in front of the ghost, he is still unsure about it. He has already been depressed and he can b…