Judaism regards the violation of divine commandments to be a sin. Judaism teaches that sin is an act, and not a state of being. Humankind was not created with an inclination to do evil, but has that inclination "from his youth"(Genesis 8:21). People do have the ability to master this inclination (Genesis 4:7) and choose good over evil (conscience)(Psalm 37:27).^[5] Judaism uses the term "sin" to include violations of Jewish law that are not necessarily a lapse in morality. According to the Jewish encyclopedia, "Man is responsible for sin because he is endowed with free will ("behirah"); yet he is by nature frail, and the tendency of the mind is to evil: "For the imagination of man's heart is evil from his youth" (Gen. viii. 21; Yoma 20a; Sanh. 105a). Therefore God in His mercy allowed people to repent and be forgiven."^[6] Judaism holds that all people sin at various points in their lives, and hold that God tempers justice with mercy.

The generic Hebrew word for any kind of sin is avera (literally: transgression). Based on verses in the Hebrew Bible, Judaism describes three levels of sin. There are three categories of a person who commits an avera. The first one is someone who does an avera intentionally, or "B'mezid." This is the most serious category. The second is one who did an avera by accident. This is called "B'shogeg," and while the person is still responsible for their action it is considered less serious. The third category is someone who is a "Tinok Shenishba", which is a person who was raised in an environment that was assimilated or non-Jewish, and is not aware of the proper Jewish laws, or halacha. This person is not held accountable for their actions.

• Pesha (deliberate sin; in modern Hebrew: crime) or Mered (lit.: rebellion) - An intentional sin; an action committed in deliberate defiance of God; (Strong's Concordance :H6588 (פשע pesha', peh'shah). According to Strong it comes from the root (:H6586); rebellion, transgression, trespass.
• Avon (lit.: iniquity) - This is a sin of lust or uncontrollable emotion. It is a sin done knowingly, but not done to defy God; (Strong's Concordance :H5771 (avon, aw-vone). According to Strong it comes from the root (:H5753); meaning perversity, moral evil:--fault, iniquity, mischief.
• Cheit - This is an unintentional sin, crime or fault. (Strong's Concordance :H2399 (חַטָּא chate). According to Strong it comes from the root khaw-taw (:H2398, H2403) meaning "to miss, to err from the mark (speaking of an archer), to sin, to stumble."

Judaism holds that no human being is perfect, and all people have sinned many times. However, certain states of sin (i.e. avon or cheit) do not condemn a person to damnation; only one or two truly grievous sins lead to anything approaching the standard conception of hell. The scriptural and rabbinic conception of God is that of a creator who tempers justice with mercy. Based on the views of Rabbeinu Tam in the Babylonian Talmud (tractate Rosh HaShanah 17b), God is said to have thirteen attributes of mercy:

1. God is merciful before someone sins, even though God knows that a person is capable of sin.
2. God is merciful to a sinner even after the person has sinned.
3. God represents the power to be merciful even in areas that a human would not expect or deserve.
4. God is compassionate, and eases the punishment of the guilty.
5. God is gracious even to those who are not deserving.
6. God is slow to anger.
7. God is abundant in kindness.
8. God is the god of truth, thus we can count on God's promises to forgive repentant sinners.
9. God guarantees kindness to future generations, as the deeds of the righteous patriarchs (Abraham, Isaac and Jacob) have benefits to all their descendants.
10. God forgives intentional sins if the sinner repents.
11. God forgives a deliberate angering of Him if the sinner repents.
12. God forgives sins that are committed in error.
13. God wipes away the sins from those who repent.

As Jews are commanded in imitatio Dei, emulating God, rabbis take these attributes into account in deciding Jewish law and its contemporary application.

A classical rabbinic work, Midrash Avot de Rabbi Natan, states:

The Babylonian Talmud teaches that "Rabbi Yochanan and Rabbi Eleazar both explain that as long as the Temple stood, the altar atoned for Israel, but now, one's table atones [when the poor are invited as guests]." (Tractate Berachot, 55a.)

The traditional liturgy of the Days of Awe (the High Holy Days; i.e. Rosh Hashanah and Yom Kippur) states that prayer, repentance and tzedakah (charitable actions) are ways to repent for sin. In Judaism, sins committed against people (rather than against God or in the heart) must first be corrected and put right to the best of a person's ability; a sin which has not also been put right as best as possible cannot truly be said to be repented.