What is the parable of sheep and goats you refer to? Matthew 25? It's about faith, just like Paul also says. The good faith of a faithful person works to multiply faith, whereas a bit of faith given, not trusted and hidden away is worthless.

Matthew 25:31 "When the Son of Man comes in his glory, and all the angels with him, he will sit on his throne in heavenly glory.
32 All the nations will be gathered before him, and he will separate the people one from another as a shepherd separates the sheep from the goats.
33 He will put the sheep on his right and the goats on his left.
34 "Then the King will say to those on his right, 'Come, you who are blessed by my Father; take your inheritance, the kingdom prepared for you since the creation of the world.
35 For I was hungry and you gave me something to eat, I was thirsty and you gave me something to drink, I was a stranger and you invited me in,
36 I needed clothes and you clothed me, I was sick and you looked after me, I was in prison and you came to visit me.'
37 "Then the righteous will answer him, 'Lord, when did we see you hungry and feed you, or thirsty and give you something to drink?
38 When did we see you a stranger and invite you in, or needing clothes and clothe you? 39When did we see you sick or in prison and go to visit you?'
40 "The King will reply, 'I tell you the truth, whatever you did for one of the least of these brothers of mine, you did for me.'
41 "Then he will say to those on his left, 'Depart from me, you who are cursed, into the eternal fire prepared for the devil and his angels.
42 For I was hungry and you gave me nothing to eat, I was thirsty and you gave me nothing to drink,
43 I was a stranger and you did not invite me in, I needed clothes and you did not clothe me, I was sick and in prison and you did not look after me.'
44 "They also will answer, 'Lord, when did we see you hungry or thirsty or a stranger or needing clothes or sick or in prison, and did not help you?'
45 "He will reply, 'I tell you the truth, whatever you did not do for one of the least of these, you did not do for me.'
46 "Then they will go away to eternal punishment, but the righteous to eternal life."

The law does stand for all time, but no one can expect to achieve salvation through it. God gave the law to Moses in a time before a savior was given. the bible tells us repatedly of what the Hebrews experienced when they kept the law, when they did not. The law was our teacher, as Paul stated, so that we would know which way God wanted us to go, how to behave etc, what he expects of us. Faith in Jesus Christ will redeem a soul as the law could not. Faith in Jesus will multiply our own faith because of the way he reveals himself to us and leads us, which is why, all you really do need is Jesus. Knowing the written word God and the law has never hurt anyone either. It's a lot easier to read it and know it than it is to work out your salvation by repetitious trial and error. However, the Lord judges our hearts (because the law truly is impossible to keep perfectly), and saves us not by perfection in the law, but by our faith in him, our love of him, and our willingness to obey him even though we might fail. Jesus came, lived this life as a man, experienced life as a man, walked this earth and died for our sins, paid the price for us... and one by one, through faith he redeems us. Prior to that, the belief of most Jews was that no matter how good a life a person led, scheol was the final destination. Jesus is the son of God, hell had it's chance and could not keep him. Thus by him, we are also saved.