Jesus said 2 commandments, love God and love your fellow man, that this is the law and the prophets. The first 4 commandments deal with loving God, the last 6 with loving our fellow man. Paul said that the Law was our 'schoolmaster' to bring us to Christ. We look at the Law like a mirror, it shows us every wrinkle, blemish, wart, every sin. It is like a whip, or hammer driving us to Christ. We see in the Law how we sin and fall short of God's Holiness, thus being in need of a Saviour. Paul said He could keep the commandments pretty well, except covetousness slayed him. He didn't commit adultery, lie, steal, etc., but he coveted, he wanted to do those things.
Once the Law shows us our unholiness compared to a Holy God, like the doctor tells us we have cancer and will die, Grace comes in with the cure! Trusting alone in Christ alone, accepting the free gift of salvation, His paying for our sins in our place, His righteousness in place of our own. Repenting from the sin of unbelief to believing in, trusting in Christ's work on the cross for us. We are under grace, and free from the law of sin and death.
In Acts (and Galatians) people tried to corrupt the simplicity of the Gospel by adding other laws to simple faith in Christ for salvation. Paul sharply rebuked these people. Grace by faith is the only way.
15:5 But there rose up certain of the sect of the Pharisees which believed, saying, That it was needful to circumcise them, and to command them to keep the law of Moses.
15:6 And the apostles and elders came together for to consider of this matter.
15:7 And when there had been much disputing, Peter rose up, and said unto them, Men and brethren, ye know how that a good while ago God made choice among us, that the Gentiles by my mouth should hear the word of the gospel, and believe.
15:8 And God, which knoweth the hearts, bare them witness, giving them the Holy Ghost, even as he did unto us; 15:9 And put no difference between us and them, purifying their hearts by faith.
15:10 Now therefore why tempt ye God, to put a yoke upon the neck of the disciples, which neither our fathers nor we were able to bear? 15:11 But we believe that through the grace of the LORD Jesus Christ we shall be saved, even as they.
15:19 Wherefore my sentence is, that we trouble not them, which from among the Gentiles are turned to God: 15:20 But that we write unto them, that they abstain from pollutions of idols, and from fornication, and from things strangled, and from blood.
15:24 Forasmuch as we have heard, that certain which went out from us have troubled you with words, subverting your souls, saying, Ye must be circumcised, and keep the law: to whom we gave no such commandment: 15:28 For it seemed good to the Holy Ghost, and to us, to lay upon you no greater burden than these necessary things; 15:29 That ye abstain from meats offered to idols, and from blood, and from things strangled, and from fornication: from which if ye keep yourselves, ye shall do well. Fare ye well.
(King James Bible, Acts)
2:16 Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
2:21 I do not frustrate the grace of God: for if righteousness come by the law, then Christ is dead in vain.
3:1 O foolish Galatians, who hath bewitched you, that ye should not obey the truth, before whose eyes Jesus Christ hath been evidently set forth, crucified among you? 3:2 This only would I learn of you, Received ye the Spirit by the works of the law, or by the hearing of faith? 3:3 Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh?
3:8 And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed.
3:9 So then they which be of faith are blessed with faithful Abraham.
3:10 For as many as are of the works of the law are under the curse: for it is written, Cursed is every one that continueth not in all things which are written in the book of the law to do them.
3:11 But that no man is justified by the law in the sight of God, it is evident: for, The just shall live by faith.
3:12 And the law is not of faith: but, The man that doeth them shall live in them.
3:13 Christ hath redeemed us from the curse of the law, being made a curse for us: for it is written, Cursed is every one that hangeth on a tree: 3:14 That the blessing of Abraham might come on the Gentiles through Jesus Christ; that we might receive the promise of the Spirit through faith.
3:22 But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe.
3:23 But before faith came, we were kept under the law, shut up unto the faith which should afterwards be revealed.
3:24 Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith.
3:25 But after that faith is come, we are no longer under a schoolmaster.
3:26 For ye are all the children of God by faith in Christ Jesus.
3:27 For as many of you as have been baptized into Christ have put on Christ.
4:4 But when the fulness of the time was come, God sent forth his Son, made of a woman, made under the law, 4:5 To redeem them that were under the law, that we might receive the adoption of sons.
4:9 But now, after that ye have known God, or rather are known of God, how turn ye again to the weak and beggarly elements, whereunto ye desire again to be in bondage? 4:10 Ye observe days, and months, and times, and years.
4:11 I am afraid of you, lest I have bestowed upon you labour in vain.
4:16 Am I therefore become your enemy, because I tell you the truth? 4:17 They zealously affect you, but not well; yea, they would exclude you, that ye might affect them.
4:21 Tell me, ye that desire to be under the law, do ye not hear the law?
5:1 Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage.
5:2 Behold, I Paul say unto you, that if ye be circumcised, Christ shall profit you nothing.
5:3 For I testify again to every man that is circumcised, that he is a debtor to do the whole law.
5:4 Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace.
5:5 For we through the Spirit wait for the hope of righteousness by faith.
5:6 For in Jesus Christ neither circumcision availeth any thing, nor uncircumcision; but faith which worketh by love.
5:7 Ye did run well; who did hinder you that ye should not obey the truth? 5:8 This persuasion cometh not of him that calleth you.
5:9 A little leaven leaveneth the whole lump.
5:10 I have confidence in you through the Lord, that ye will be none otherwise minded: but he that troubleth you shall bear his judgment, whosoever he be.
5:11 And I, brethren, if I yet preach circumcision, why do I yet suffer persecution? then is the offence of the cross ceased.
5:12 I would they were even cut off which trouble you.
Actually, the whole third, fourth, and fifth chapters of Galatians are a strong rebuke to those who would trouble us with this issue, and would help people understand how we are freely saved by faith and not by the Law. The Bible says also not to judge others in holy days, sabbaths, meat, drink, etc. Loving God and our fellow man is good, making legalistic rules and tying them in with our salvation, corrupting the gospel message is vehemently warned against by the Bible, Paul in Galatians 5 said he wished these people who troubled them were even cut off.