“The first use of the law is to manifest to man his guilt. When God intends to save a man, the first thing he does with him is to send the law to him, to show him how guilty, how vile, how ruined he is, and in how dangerous a position. . . . The spirit of the law condemns us. And this is its useful property; it humbles us, makes us know we are guilty, and so are we led to receive the Savior.”
“Now, the second. The law serves to slay all hope of salvation of a reformed life. Most men when they discover themselves to be guilty, avow that they will reform. They say, ‘I have been guilty and have deserved God’s wrath, but for the future I will seek to win a stock of merits which shall counterbalance all my old sins.’ In steps the law, puts its hand on the sinner’s mouth, and says, ‘Stop, you cannot do that, it is impossible.’ I will show you how the law does this. It does it partly thus, by reminding the man that future obedience can be no atonement for past guilt.”
“And now, a step further. You that know the grace of God can follow me in this next step. The law is intended to show man the misery which will fall upon him through his sin. . . . The law was sent on purpose to do that. But, you will ask, ‘Why that misery?’ I answer, that misery was sent for this reason: that I might then be made to cry to Jesus. Our heavenly Father does not usually make us seek Jesus till he has whipped us clean out of all our confidence; he cannot make us in earnest after heaven till he has made us feel something of the intolerable tortures of an aching conscience, which has foretaste of hell.”
Fourth, “It was sent into the world to shew the value of a Saviour. . . . the law makes Christ appear the fairer and more heavenly. I hear the law of God curse, but how harsh its voice. Jesus says, ‘come unto me;’ oh, what music! all the more musical after the discord of the law. I see the law condemns; I behold Christ obeying it. Oh! how ponderous that price - when I know how weighty was the demand! I read the commandments, and I find them strict and awfully severe - oh! how holy must Christ have been to obey all these for me! Nothing makes me value my Savior more than seeing the law condemn me. When I know this law stands in my way, and like a flaming cherubim will not let me enter paradise, then I can tell how sweetly precious must Jesus Christ’s righteousness be, which is a passport to heaven, and gives me grace to enter there.”
Fifth, “And, lastly, ‘Wherefore serveth the law.’ It was sent into the world to keep Christian men from self-righteousness. Christian men - do they ever get self-righteous? Yes, that they do. The best Christian man in the world will find it hard work to keep himself from boasting, and from being self righteous.” Thank you, Mr. Spurgeon. It is this last use of the law that pertains to our subject of antinomianism, the use of the law to keep Christian men from self-righteousness.
BIBLICALLY, legalism is keeping the law for salvation. Some charge that anyone that keeps a list of do’s and don’ts is a legalist. NOT SO! God keeps a list of do’s and don’ts in the Word, and He is not a legalist. Lists are not wrong! If a person is attempting to gain salvation by keeping those lists, then they are legalistic.” Derickson is correct in what he says. Legalism is primarily the attempt to keep the law to gain salvation, and in Galatians 3.2 Paul rebukes the Galatians, genuinely converted people, who allowed themselves to come under the influence of legalists who confused them about how they had themselves gotten converted: “This only would I learn of you, Received ye the Spirit by the works of the law, or by the hearing of faith?”
In addition, a secondary legalism plagues Christians. It is not the view that a sinner is saved by works of the law, but the view that a Christian is spiritual by works of the law, or that a Christian becomes spiritually mature by works of the law. The very next verse, Galatians 3.3, addresses that error: “Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh?” In other words, “Are you so foolish that you think what the Spirit started the flesh can finish, that the law can bring about your maturity even though it could not bring about your conversion?” Therefore, legalism, in both its forms, is an attempt to use the law in an unauthorized and illegitimate way, a way that is not sanctioned by scripture, a way that interferes with and excludes the vital work of the Holy Spirit, a way that relies upon one’s own flesh to accomplish what only the Spirit of God is capable of doing, either in regenerating the lost man or in maturing the believer.
To restate, since so many these days are confused over this issue, legalism is not the use of the law. There are legitimate uses of the law. Legalism is the misuse of the law to obtain salvation or the misuse of the law to obtain spirituality and Christian growth.
 Charles H. Spurgeon, Metropolitan Tabernacle Pulpit, Volume 3, Sermon 128, (Pasadena, Texas: Pilgrim Publishers).
 Stanley Derickson, Derickson’s Notes On Theology, (Albany, OR: AGES Software, Version 1.0, 1997)