If an omission happens deliberately and freely, it is considered a sin. ... A person may be guilty of a sin of omission if he fails to do something which he is able to do and which he ought to do because he has put himself into a state or situation whereby he is unable to complete the action.

Are there sins of omission?

A sin of omission is a sin committed because of neglecting to do what is right. They are good works left undone. Works that God expects us to do, but we don't do them. Examples could include not praying, not forgiving others, or not confessing your faith in Christ and His word to others when you have the opportunity.

What is not considered a sin?

Sins committed out of lack of knowledge are not considered sins, since a sin cannot be a sin if the one who committed it did not know it was wrong. Unintentional sins are considered less severe sins. Sins between people are considered much more serious in Judaism than sins between man and God.