Because we have been given God's own Spirit, He who created the ten commandments and all the others. Does any Christian need to be told not to murder, not to steal, etc? Instead of the written commands and ordinances...
Ephesians 2:14-16, "For he is our peace; in his flesh he has made both into one and has broken down the dividing wall, that is, the hostility between us, abolishing the law with its commandments and ordinances, that he might create in himself one new humanity in place of the two, thus making peace, and might reconcile both to God in one body through the cross, thus putting to death that hostility through it."
I mean, think about it for a minute. Do Christians refrain from murdering people because there is a command not to, or do they do so because they love their neighbors?
Philippians 4:6-8, "Do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and your minds in Christ Jesus.
Finally, brothers and sisters, whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is pleasing, whatever is commendable, if there is any excellence and if there is anything worthy of praise, think about these things."
This is the exact opposite of relying on some external law or command.
The Ten Commandments are are a part of God's commands that we are to walk in obedience to. If it weren't for these commands of God then no one would know not to kill, steal and covet are wrong doings. It would only become a natural part of the worldly ways. I can't believe we are even discussing not following the ten commandments lke they are done away with.
Exo 20:1 And God spake all these words, saying,
Exo 20:2 I am the LORD thy God, which have brought thee out of the land of Egypt, out of the house of bondage.
Exo 20:3 Thou shalt have no other gods before me.
Exo 20:4 Thou shalt not make unto thee any graven image, or any likeness of any thing that is in heaven above, or that is in the earth beneath, or that is in the water under the earth:
Exo 20:5 Thou shalt not bow down thyself to them, nor serve them: for I the LORD thy God am a jealous God, visiting the iniquity of the fathers upon the children unto the third and fourth generation of them that hate me;
Exo 20:6 And shewing mercy unto thousands of them that love me, and keep my commandments.
Exo 20:7 Thou shalt not take the name of the LORD thy God in vain; for the LORD will not hold him guiltless that taketh his name in vain.
Exo 20:8 Remember the sabbath day, to keep it holy.
Exo 20:9 Six days shalt thou labour, and do all thy work:
Exo 20:10 But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates:
Exo 20:11 For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.
Exo 20:12 Honour thy father and thy mother: that thy days may be long upon the land which the LORD thy God giveth thee.
Exo 20:13 Thou shalt not kill.
Exo 20:14 Thou shalt not commit adultery.
Exo 20:15 Thou shalt not steal.
Exo 20:16 Thou shalt not bear false witness against thy neighbour.
Exo 20:17 Thou shalt not covet thy neighbour's house, thou shalt not covet thy neighbour's wife, nor his manservant, nor his maidservant, nor his ox, nor his ass, nor any thing that is thy neighbour's.
Exo 20:18 And all the people saw the thunderings, and the lightnings, and the noise of the trumpet, and the mountain smoking: and when the people saw it, they removed, and stood afar off.
Exo 20:19 And they said unto Moses, Speak thou with us, and we will hear: but let not God speak with us, lest we die.
Exo 20:20 And Moses said unto the people, Fear not: for God is come to prove you, and that his fear may be before your faces, that ye sin not.
Exo 20:21 And the people stood afar off, and Moses drew near unto the thick darkness where God was.