It depends on your religious viewpoint. In Catholicism, less serious sins are called venial sins and do not require absolution, while major transgressions are mortal sins and require a confession.
In the New testament Jesus says that there is a sin that is unforgivable, blasphemy of the holy spirit. He also says that a person who misleads a child should die. All sin separates from God but some make him madder than others.
