What is 'SIN' ?

Genesis 2:17
But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.

What is 'sin'? How do we define 'sin' under the sun?

Today, we find many religions in this world that have defined 'sin' according to their righteousness. In other words, 'sin' is defined by humans by using their own righteousness.

'Sin' defined based on human righteousness has offended God, the Creator, and pushed humans to ask the foolish questions such as 'If there is a God, how could this happen?' 'Where was God when this disaster came upon the land?' 'If there is a God, why poor people? why blind people? why crippled? why disabled? why tsunami? why earthquakes? why wars? and so many, many 'why's'.

Humans who have defined 'sin', always judge things according to their righteousness. But if we come to know the right definition of 'sin' we never offend God foolishly.

The right definition of 'sin' is 'not doing what God has commanded'. In other words, breaking the commandments or law of God is defined as 'sin'.

If there were no commandments or law of God, there would be nothing called 'sin'.Romans 5:13
For until the law sin was in the world: but sin is not imputed when there is no law.

For example let's look at the sin of Adam. Eating a fruit from a tree is not a sin according to the definition of 'sin' based on human righteousness. But when Adam ate from the tree of knowledge of good and evil, he was considered as a sinner as God had told him not to eat from it as mentioned in the opening scripture. Thus an ordinary act which is not considered as a sin according to human righteousness became a sin for Adam as God had told Adam not to do it.

The below scriptures shows what man was commanded to eat after God created them as male and female and what animals were commanded to eat in the very beginning. According to the below commandments, man cannot eat either animals or green herb, which was the food of animals.

Genesis 1:29-3029 And God said, Behold, I have given you every herb bearing seed, which is upon the face of all the earth, and every tree, in the which is the fruit of a tree yielding seed; to you it shall be for meat. 30 And to every beast of the earth, and to every fowl of the air, and to every thing that creepeth upon the earth, wherein there is life, I have given every green herb for meat: and it was so.

But look at the below commandment of God given to Noah and his family just after the flood. Genesis 9:3-4
3 Every moving thing that liveth shall be meat for you; even as the green herb have I given you all things. 4 But flesh with the life thereof, which is the blood thereof, shall ye not eat.

According to the above commandment in Genesis 9:3-4, now man could eat both animals and animal's food, which is green herb. In the beginning, when Adam ate animals or green herb it was a sin and now when Noah ate them it was not a sin.

Let's look at another example. God asked the children of Israel not to murder as the sixth commandment in the Ten Commandments. God gave these commandments when the children of Israel were at the mount Sinai. Exodus 20:13
13 Thou shalt not kill.

But the same God was asking the same people to kill certain groups of people when the children of Israel came to another location.
Deuteronomy 20:17 (KJV)
17 But thou shalt utterly destroy them; namely, the Hittites, and the Amorites, the Canaanites, and the Perizzites, the Hivites, and the Jebusites; as the Lord thy God hath commanded thee:

In brief, when God asks not to kill, it is a sin if you do kill, and when God asks to kill, then it is a sin if you do not kill.

Well, how does human righteousness justify these actions? Can man be more righteous than God by judging God's commandments? Can man have any courage to make judgements according to his righteousness before the below declaration of God Almighty.
 
Deuteronomy 32:39
39 See now that I, even I, am he, and there is no god with me: I kill, and I make alive; I wound, and I heal: neither is there any that can deliver out of my hand.

Therefore, Christians should not be surprised under the frame of human righteousness, when God brings things to happen against it since it is only God who has the authority to define 'sin' as He wishes.