Why do some many christians say we can't keep all Ten Commandments?

I really believe by God's grace found only in Jesus, we can keep them as he gives us power. The scripture speaks of Jesus as a Savior from sin(Matt.1;21). Without faith in him to refresh us by prayer and devotion and scripture readying daily. We become weak in the flesh and become subject to the Law of sin. We all sin but with Jesus saving power we can be free from its slave mastering grip. To keep any of the ten commandments we have to be born again and have accepted the guilt of breaking them. This requires confession that you broke all and all have sinned.1john 3;4 states the result of braking the law is sin. We just need not to be partial to God's law if one is broken then all is broken by the sinner James2;10-12. So when it comes to murder or adultery its all consider sin. An habitual sin is allowing it to have rule over you continually and just because it is taken lightly or ignored doesn't mean God won't hold us accountable. Many Christians oppose the seventh day sabbath as a day of worship but fail to recognize God wants his Law to never be changed or alter or carried out in partial. So this claim you cant keep them all is only true when your out side of God's grace to save you. Who really would consider that God could write Ten but erase one from it ? This is the longest one in the middle and has remember in front of this 4th commandment. If he did that it would had to been changed before Jesus died and sealed the new covenant in his blood. As it remains to this very day we find no words before he died that he was going to change it. Nor do we find any of the other commandments changed because it is the heart of God's government it stands a law of love. Many excuses you will hear for not keeping the Law , it was nailed, it was abolished, destroyed, changed and its a . There was two Laws given at Sinai one whole law with nothing added to it(Ten Commandments) and then there was the law writing by moses. One placed in the Arc of the covenant under the mercy seat and the other on the side of the Arc where it should be read daily. These two separate laws are always fused together when the sabbath day comes in mind by pastors and clergy. Heb.8;& 10; prophetic message with a Promise God says he would write his laws in our hearts and minds. As part of the new covenant with Israel and they knew his laws and sense we are grafted in according to Paul we are spiritual Israel by faith. Read Romans, Gal., Col., Eph., and hebrews on apostle Paul words.