1. Sins of Omission
The omission of good is no less reprehensible than the commission of evil.
~ Plutarch (AD )
Plutarch was a noted Greek biographer and essayist.
(James 4:13-17), “Come now, you who say, "Today or tomorrow we will go to such and such a city, spend a year there, buy and sell, and make a profit"; 14 whereas you do not know what will happen tomorrow. For what is your life? It is even a vapor that appears for a little time and then vanishes away. 15 Instead you ought to say, "If the Lord wills, we shall live and do this or that." 16 But now you boast in your arrogance. All such boasting is evil. 17 Therefore, to him who knows to do good and does not do it, to him it is sin.”
To live without ordering one’s life after the Lord’s will is sin against Almighty God. 
What the Lord commands us is “good”, and the very existence of His commandment obligates us to obey
(Matthew 7:21-23), “Not everyone who says to Me, 'Lord, Lord,' shall enter the kingdom of heaven, but he who does the will of My Father in heaven. 22 Many will say to Me in that day, 'Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name? ' 23 And then I will declare to them, 'I never knew you; depart from Me, you who practice lawlessness! ' 
To omit the stated will of God from our life brings sin into our life.

2. Important Principles…
The Lord does not expect more of you than you are able to give (2 Corinthians 8:12)
A part of spiritual growth is to increase your capacity to do good! (Hebrews 5:12-14)
Ignorance is not an acceptable excuse. We must know what God expects of us! (Leviticus 5:17-19; Ephesians 5:17)
(2 Corinthians 8:12), “For if there is first a willing mind, it is accepted according to what one has, and not according to what he does not have.”
(Hebrews 5:12-14), “For though by this time you ought to be teachers, you need someone to teach you again the first principles of the oracles of God; and you have come to need milk and not solid food. 13 For everyone who partakes only of milk is unskilled in the word of righteousness, for he is a babe. 14 But solid food belongs to those who are of full age, that is, those who by reason of use have their senses exercised to discern both good and evil.
The New Testament affirms that the spiritually mature have the capacity for greater service. They are held responsible for that service. (cf. James 3:1, “My brethren, let not many of you become teachers, knowing that we shall receive a stricter judgment.”)
(Leviticus 5:17-19), “If a person sins, and commits any of these things which are forbidden to be done by the commandments of the Lord, though he does not know it, yet he is guilty and shall bear his iniquity. 18 And he shall bring to the priest a ram without blemish from the flock, with your valuation, as a trespass offering. So the priest shall make atonement for him regarding his ignorance in which he erred and did not know it, and it shall be forgiven him. 19 It is a trespass offering; he has certainly trespassed against the Lord.“
(Ephesians 5:17), “Therefore do not be unwise, but understand what the will of the Lord is.”   

3. Sins of Omission The Priest and the Levite (Luke 10:30-37)
Here are a few Scriptures that illustrate sins of omission
(James 4:17), “Therefore, to him who knows to do good and does not do it, to him it is sin.”
Luke 10:30-37, “Then Jesus answered and said:" A certain man went down from Jerusalem to Jericho, and fell among thieves, who stripped him of his clothing, wounded him, and departed, leaving him half dead. 31 Now by chance a certain priest came down that road. And when he saw him, he passed by on the other side. 32 Likewise a Levite, when he arrived at the place, came and looked, and passed by on the other side. 33 But a certain Samaritan, as he journeyed, came where he was. And when he saw him, he had compassion. 34 So he went to him and bandaged his wounds, pouring on oil and wine; and he set him on his own animal, brought him to an inn, and took care of him. 35 On the next day, when he departed, he took out two denarii, gave them to the innkeeper, and said to him, 'Take care of him; and whatever more you spend, when I come again, I will repay you. ' 36 So which of these three do you think was neighbor to him who fell among the thieves?“ 37 And he said, "He who showed mercy on him.“ Then Jesus said to him, " Go and do likewise."
The priest and the Levite sinned by not doing what they knew to be good and right.
They sinned by failing to love their neighbor.

4. Sins of Omission The Priest and the Levite (Luke 10:30-37)
The One Talent Man (Matthew 25:24-30)
Matthew 25:24-30, “" Then he who had received the one talent came and said, 'Lord, I knew you to be a hard man, reaping where you have not sown, and gathering where you have not scattered seed. 25 And I was afraid, and went and hid your talent in the ground. Look, there you have what is yours. '26 " But his lord answered and said to him, 'You wicked and lazy servant, you knew that I reap where I have not sown, and gather where I have not scattered seed. 27 So you ought to have deposited my money with the bankers, and at my coming I would have received back my own with interest. 28 So take the talent from him, and give it to him who has ten talents. 29 ' For to everyone who has, more will be given, and he will have abundance; but from him who does not have, even what he has will be taken away. 30 And cast the unprofitable servant into the outer darkness. There will be weeping and gnashing of teeth. '
The man who received one talent from his master knew he was responsible for using it, but he chose to bury it instead of using it for his master’s profit. 
He knew to do good, but he did not do it.
He sinned against his master and was cast into punishment.

5. Sins of Omission The Priest and the Levite (Luke 10:30-37)
The One Talent Man (Matthew 25:24-30)
The Disciple who is Indifferent to His Brethren (Matthew 25:41-46)
Matthew 25:41-46, “Then He will also say to those on the left hand, 'Depart from Me, you cursed, into the everlasting fire prepared for the devil and his angels: 42 for I was hungry and you gave Me no food; I was thirsty and you gave Me no drink; 43 I was a stranger and you did not take Me in, naked and you did not clothe Me, sick and in prison and you did not visit Me. '44 " Then they also will answer Him, saying, 'Lord, when did we see You hungry or thirsty or a stranger or naked or sick or in prison, and did not minister to You? ' 45 Then He will answer them, saying, 'Assuredly, I say to you, inasmuch as you did not do it to one of the least of these, you did not do it to Me. ' 46 And these will go away into everlasting punishment, but the righteous into eternal life."
Jesus warned that many will be delivered to everlasting fire because they failed to do what was right toward their brethren.

6. Conclusion Every God given responsibility is “good.”
We must do them! If we do not, we sin!
(cf. James 4:17)
James 4:17, “Therefore, to him who knows to do good and does not do it, to him it is sin.”