We sin by "deed" when this deed is contrary to God's commandment.

If a person indulges in gluttony, drunkenness, and delicacies, then he sins against the commandment of God: "Thou shalt not make for thyself an idol or any likeness."

Theft, robbery, murder and other similar acts are sins by deed.

Sin is "by word" when this word is contrary to the will of God.

For example, idle conversations, words, songs are sins in word.

The Lord Jesus Christ forbids these sins, saying: "For every idle word that men speak, they will give account in the day of judgment" (Matt. 12:36).

If we revile our neighbor with words, reproach him, scold him, or speak lies about him behind his back, complain about him unjustly, slander out of hatred, then we sin against the commandment of God: "Do not obey your friend's false testimony."

These sins in word are more harmful than many sins in deed and can stand side by side with murder.

We sin "in thought" if we have any desires contrary to love for our neighbor, when we act against the commandment of God: "Do not covet anything that belongs to your neighbor."

Sins of thought are as grave as sins of deed and word, and are strictly forbidden by Holy Scripture.

Sins by "knowledge" are those that we commit, knowing that they are forbidden by the law of God, we commit them according to our passions – out of pride, malice, laziness, and the like – and we justify ourselves with false arguments.

Those who act in this way are worthy of the same sentence that the master pronounced on his wicked and slothful servant: "Wicked servant and slothful!"

You knew that I reap where I did not sow, and I gather where I did not scatter...

cast the worthless servant into outer darkness: there will be weeping and gnashing of teeth (Matt. 25:26-30).