What Is Sin?

1 John 3:4

Whosoever committeth sin transgresseth also the law: for sin is the transgression of the law.

Sin is breaking the law: The verse connects sin directly with breaking God's law, defining sin as an action that goes against it.

If you don't follow the commandments/laws you are committing sin.

Matthew 7:15-20

15 Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.
16 Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles?
17 Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.
18 A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit.
19 Every tree that bringeth not forth good fruit is hewn down, and cast into the fire.
20 Wherefore by their fruits ye shall know them.

Deuteronomy 8:1-6

1 All the commandments which I command thee this day shall ye observe to do, that ye may live, and multiply, and go in and possess the land which the LORD sware unto your fathers.
2 And thou shalt remember all the way which the LORD thy God led thee these forty years in the wilderness, to humble thee, and to prove thee, to know what was in thine heart, whether thou wouldest keep his commandments, or no.
3 And he humbled thee, and suffered thee to hunger, and fed thee with manna, which thou knewest not, neither did thy fathers know; that he might make thee know that man doth not live by bread only, but by every word that proceedeth out of the mouth of the LORD doth man live.
4 Thy raiment waxed not old upon thee, neither did thy foot swell, these forty years.
5 Thou shalt also consider in thine heart, that, as a man chasteneth his son, so the LORD thy God chasteneth thee.
6 Therefore thou shalt keep the commandments of the LORD thy God, to walk in his ways, and to fear him.

James 2:18-20

18 Yea, a man may say, Thou hast faith, and I have works: shew me thy faith without thy works, and I will shew thee my faith by my works.
19 Thou believest that there is one God; thou doest well: the devils also believe, and tremble.
20 But wilt thou know, O vain man, that faith without works is dead?