The idea of some kind of sin nature — along with many other ideas — was devel­oped through­out the lat­ter part of the early cen­turies. Spare me from dig­ging out the “when”, you can find plenty of info on Google if you dig hard enough.

The Jew­FAQ has a very good arti­cle about what Jews think about human nature. Here is the link, read “The Dual Nature” portion:

http://www.jewfaq.org/human.htm

The idea of “sin nature” leads to such dam­ag­ing ideas held by some Chris­t­ian groups that babies who die will go to hell because they don’t believe in Jesus. Other groups claim God will do it right, but can­not give spe­cific answers in what way. Per­haps God will be gra­cious with those who are inca­pable to believe. This the­ol­ogy also can­not account for the right­eous before Jesus, or even Moses or well before him. Before Abra­ham the idea of the Mes­sianic King­dom wasn’t even revealed, and Abraham’s hope was only that God will one day gives him and his descen­dants the land of Canaan. No Mes­siah, the son of David men­tioned, such idea was a later development.

Or what about Noah and his sons who were just too happy to sur­vive the flood, and their only hope was that God would never again destroy the world by water. Per­haps we shall even go back to before the flood and see the right­eous there with­out any hope about some kind of promised land with a davidic king rul­ing it forever.

One can only argue that the hope that some kind of “seed” of a woman will crash the head of the ser­pent was present in those days, but we for­get that we read NT the­ol­ogy back into the text which does injus­tice to it. Devel­op­ing the­ol­ogy should work the other way around. Inter­pret the text first, then explain the NT usage. Argu­ing that the ancient peo­ple had the under­stand­ing of Chris­tians is very weak.
How­ever, if there is no such a thing as “sin nature”, then our whole the­ol­ogy needs to be reviewed, but at the end we will end up with a the­ol­ogy much sim­pler and cleaner than what we inher­ited from our spir­i­tual forefathers.

So here is an alter­na­tive view on the sub­ject. Every child born to this world needs train­ing. He needs to learn to speak, to walk, to eat inde­pen­dently, to do what is right — oh, yes, it is the duty of the par­ents to teach their kids about that. Just give into the hand of a few months old baby a spoon of food and see what a mess he will do on his face.

So the child is not born with some kind of sin nature, he sim­ply doesn’t know how to do right. He needs to be trained. In Jew­ish cul­ture chil­dren were taught the Torah from age six, and dur­ing their train­ing they were not required to observe it, though they were encour­aged to observe as many com­mands as they could. How­ever, until they became the “sons/daughters of the com­mand­ment” (bar mitz­vah — age 13 for boys and age 12 for girls), they were not respon­si­ble for their own sins. The right­eous­ness of their par­ents cov­ered their sins. Once they reached that age they were respon­si­ble for fully keep­ing the law and their own sins.

We may call into mind the exam­ple of Job — though the book is prob­a­bly the ear­li­est, pre­dat­ing even Abra­ham. There we see Job offer­ing up sac­ri­fices for his own children:

Job 1:4 His sons used to go and hold a feast in the house of each on his day; and they would send and invite their three sis­ters to eat and drink with them. 5 And when the days of the feast had run their course, Job would send and sanc­tify them, and he would rise early in the morn­ing and offer burnt offer­ings accord­ing to the num­ber of them all; for Job said, “It may be that my sons have sinned, and cursed God in their hearts.” Thus Job did continually.

It was the father who cov­ered for the sins of his own chil­dren. Up to a cer­tain age they were not respon­si­ble for their own sins. They were not yet prop­erly trained to do right.

Another exam­ple I may bring is from Isaiah:

Isa. 14:10 Again the LORD spoke to Ahaz, 11 “Ask a sign of the LORD your God; let it be deep as Sheol or high as heaven.” 12 But Ahaz said, “I will not ask, and I will not put the LORD to the test.” 13 And he said, “Hear then, O house of David! Is it too lit­tle for you to weary men, that you weary my God also? 14 There­fore the Lord him­self will give you a sign. Behold, a young woman is with child and shall bear a son {taken from the NRSV, the best schol­arly trans­la­tion}, and shall call his name Imman’u-el. 15 He shall eat curds and honey when he knows how to refuse the evil and choose the good. 16 For before the child knows how to refuse the evil and choose the good, the land before whose two kings you are in dread will be deserted.

This is a sign given to Ahab. The sign is not about the vir­gin birth of a child, but that a child will be born to a woman who was already preg­nant, and before the child learned to reject evil and choose good the two kings Ahab feared would desert the land.

Too bad, this is not a prophecy about a virgin-born Mes­siah, the only way Matthew can apply this pas­sage in his gospel is by tak­ing the Drash mean­ing of the text (tak­ing an idea from a text and apply­ing it in a dif­fer­ent, unre­lated con­text): the birth of the child means God has not aban­doned his peo­ple. Indeed, under Roman occu­pa­tion (which to the Jews meant God’s dis­plea­sure) the birth of the Deliv­erer meant God was still with His people.

See the ful­fill­ment of this sign in the chap­ters that fol­low, for example:

Isa. 8:3 And I went to the prophet­ess, and she con­ceived and bore a son.

Even though her son was named dif­fer­ently (so was Jesus), we see Imman’u-el in Chap­ter 8:

Isa. 8:7 … behold, the Lord is bring­ing up against them the waters of the River, mighty and many, the king of Assyria and all his glory; and it will rise over all its chan­nels and go over all its banks; 8 and it will sweep on into Judah, it will over­flow and pass on, reach­ing even to the neck; and its out­spread wings will fill the breadth of your land, O Imman’u-el.…”

Isa. 8:9 Be bro­ken, you peo­ples, and be dis­mayed; give ear, all you far coun­tries; gird your­selves and be dis­mayed; gird your­selves and be dis­mayed. 10 Take coun­sel together, but it will come to nought; speak a word, but it will not stand, for God is with us.

Here we find the com­fort­ing words in a desparate sit­u­a­tion: God is with us = Imman’u-el. The child served as a sign that God was with His people.

How­ever, the point I wish to make is that the child had to be trained:

Isa. 14:16 …before the child knows how to refuse the evil and choose the good…

The untrained per­son is left to his own devices to work out his own moral code. Obvi­ously, he will get some things right, oth­ers wrong. The per­son with­out the light of the law of God is like liv­ing in dark­ness. Right­eous­ness requires train­ing — and the desire to learn:

Deut. 6:4 Hear, O Israel: The LORD our God is one LORD; 5 and you shall love the LORD your God with all your heart, and with all your soul, and with all your might. 6 And these words which I com­mand you this day shall be upon your heart; 7 and you shall teach them dili­gently to your chil­dren, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise. 8 And you shall bind them as a sign upon your hand, and they shall be as frontlets between your eyes. 9 And you shall write them on the door­posts of your house and on your gates.

Give an unskilled per­son full access to the bank’s data­base and by his best efforts he will make a mess of it. Such a com­plex job requires proper train­ing before a per­son can do such a work.

So the one who want to live right­eously must learn the ways of right­eous­ness, “how to refuse the evil and choose the good”.

If there is “sin nature”, one is not respon­si­ble for his sins, for he could not do any bet­ter. The fish can only live under water, and the ele­phant must live on dry land. They have such a nature. Shall we blame the fish for liv­ing under water? Shall we blame the ele­phant for being too heavy or for hav­ing large ears?

How­ever, if there is no such a thing, then sud­denly we are all respon­si­ble for what we do. Of course, then we need to rework our the­ol­ogy and return to the Jew­ish teach­ing of Jesus and the apostles.

Not even Paul sup­ports such an idea:

Rom 3:23 since all have sinned and fall short of the glory of God…

Notice he doesn’t say, “all were born with a sin nature”, but that all com­mit­ted sin­ful acts, and that is the very rea­son they fall short of the glory of God, which is God’s unspoiled image in man (when he cre­ated Adam). The “all” is again an exag­ger­a­tion, but you can clearly see that to Paul sin is a choice, not the act­ing out of some kind of “sin nature”. If there was such a nature, we would all fall short of the glory of God from birth, and not as a result of com­mit­ting sin­ful acts.