When I think of the word legalism, I think of these verses:
2 Corinthians 3:6 (KJV)
Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.
Hebrews 8:6 (KJV)
But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises.
Romans 7:6 (KJV)
But now we are delivered from the law, that being dead wherein we were held; that we should serve in newness of spirit, and not [in] the oldness of the letter.
Romans 8:7 (KJV)
Because the carnal mind [is] enmity against God: for it is not subject to the law of God, neither indeed can be.
So what do I get from all these? I think of my oldest son when he was being potty trained. One day, I noticed him playing with his siblings and he stopped, got up, went to the bathroom, did his business, flushed the toilet, washed his hands and went back to playing, all without him noticing me watching. It brought great joy to me!
He followed the "law" his mother and I set up, which was for his good. This is what God did for us. We didn't want him sitting in his filth. If he hadn't washed his hands I would have said something, but I didn't have to. He completed the law perfectly. My son didn't grumble or complain our law was too hard, he just did it. Jesus came and fulfilled he law and through Him we too have been counted with Him on the cross and in the grave and raised from the dead.
Galatians 2:20 (KJV)
I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.
Before Christ's actions, we were bound, prisoners of sin. After Christ's actions, we are righteous by Him, Rom 3:25;
Romans 10:4 (KJV)
For Christ [is] the end of the law for righteousness to every one that believeth.
So as in like my son, can he return to sitting in his filth? Not wash his hands? Rom 6:1 NO!
Romans 6:2 (KJV)
God forbid. How shall we, that are dead to sin, live any longer therein?
Legalists want to put us back under the harshness of the law, and grace-only wants us to do whatever we want without consequences. Both are extremes and without merit. We are to be holy as Jesus is holy. The Law is the ministry of death, 2 Cor 3:7.
Romans 2:13-15 (KJV)
(For not the hearers of the law [are] just before God, but the doers of the law shall be justified. For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves: Which shew the work of the law written in their hearts, their conscience also bearing witness, and [their] thoughts the mean while accusing or else excusing one another; )
Our new ministry is reconciliation!
2 Corinthians 5:17-21 (KJV)
Therefore if any man [be] in Christ, [he is] a new creature: old things are passed away; behold, all things are become new. And all things [are] of God, who hath reconciled us to himself by Jesus Christ, and hath given to us the ministry of reconciliation; To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them; and hath committed unto us the word of reconciliation. Now then we are ambassadors for Christ, as though God did beseech [you] by us: we pray [you] in Christ's stead, be ye reconciled to God. For he hath made him [to be] sin for us, who knew no sin; that we might be made the righteousness of God in him.