in what way is henry iv a play about atonement?

The sin that lay most heavily on Henry was the murder of Richard II, and his usurpation of the throne. Richard II's executers remain unknown, but it is widely believed that after taking control and having Richard imprisoned, Henry took the final step by ordering his death. For atonement, Henry's greatest dream is to take up the cross and go on crusade to the Holy Land, but conditions in England make it impossible.

Hal, Henry IV's heir, on the other hand leads quite a life. Having spent most of his young adulthood in the company thieves and prostitutes, Hal promises his father on his deathbed that he will be a great king; he does the same for those assembled at his coronation. Hal is determined that his reign will atone for his past.