Law and grace cannot mix because they are two totally contrary principles; legalism is a yoke of bondage that must be cast out while grace is the liberty Christ gives.
Paul pictures law and legalism in Hagar and Ishmael, who were cast out rather than given a place beside Isaac. As Les Feldick puts it, God did not tell Abraham to build Ishmael a separate tent nearby. The whole book of Galatians was written to prove that believers are not under law but under grace.
Galatians 4:30 — This verse commands, 'Cast out the bondwoman and her son,' showing that law and legalism cannot coexist with grace.
Galatians 5:1 — This verse calls believers to stand fast in Christ's liberty and not be entangled again with the yoke of bondage, which is legalism.
Romans 6:15 — Paul asks, 'Shall we sin, because we are not under the law, but under grace?' and answers 'God forbid,' showing grace is not license.
In Galatians 4, the Apostle Paul reaches back to Genesis and uses the allegory of Isaac and Ishmael. Verse 30 declares: “Nevertheless what saith the scripture? Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the free woman.” The bondwoman is not permitted to remain alongside the free woman, and her son is not to share the inheritance with the free woman's son. The same chapter had just identified believers with Isaac: “Now we, brethren, as Isaac was, are the children of promise.” Therefore the command to cast out the bondwoman applies to the believer's relationship to law and legalism. Then Galatians 5:1 commands: “Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage.” Scripture itself sets liberty and bondage against each other.
Les Feldick stresses that Paul used the allegory of Isaac and Ishmael to show why law and grace cannot coexist. Hagar and Ishmael picture the Law and legalism; Sarah and Isaac picture grace and freedom. When God told Abraham to 'cast out the bondwoman and her son,' it was not a command to put Ishmael in a nearby tent or a short distance away. Legalism, like Ishmael, must be sent away entirely. Paul wrote Galatians because Jewish believers (Judaizers) were telling Gentile believers they could not be saved unless they also kept the law. Les says Paul 'screams at that'—legalism cannot be brought into grace. Law and grace are two totally contrary principles; they will not mix. Galatians 5:1 expresses this as standing fast in Christ's liberty and not being entangled again with the yoke of bondage, which Les identifies as legalism. This liberty is not license to sin—God forbid—but freedom exercised under grace, not under the law.
God told Abraham to cast out the bondwoman and her son. Les emphasizes that God did not tell Abraham to give Ishmael a separate tent next door or a place a short distance away. Hagar and Ishmael were sent away entirely. Just as Ishmael and Isaac could have no interrelationship, law and grace cannot mix. One is of the flesh; the other is of promise.
Paul wrote Galatians because Gentile believers were being besieged by Judaizers who insisted they could not be saved unless they kept the law. Paul strongly rejected this, saying we cannot bring legalism into grace. Les points out that law and grace are two totally contrary principles and that Paul continually cries against legalism in any form.
Paul himself asks, 'Shall we sin because we are not under the law, but under grace?' and answers, 'God forbid.' Les explains that being under grace does not give license; believers are under a whole different set of circumstances. Grace does not mean we are free to sin; it means we are free from the yoke of legalism.
Cast Out the Bondwoman
Les explains that the casting out of Hagar and Ishmael pictures the Law and legalism, and he connects Galatians 4:30 and Genesis 21 to Paul's argument that law and grace cannot mix.
No Separate Tent for Ishmael
Les emphasizes that God commanded Abraham to cast out the bondwoman and her son, not to give Ishmael a separate tent, proving law and grace cannot mix.
Galatians and the Judaizers
Les points out that Paul wrote Galatians to Gentile believers being pressured by Judaizers; Paul calls out the impossibility of bringing legalism into grace.
Ishmael and Isaac Cannot Consort
Les says Ishmael stood for the law and legalism while Isaac stood for grace and freedom, so the two can have no consort or interrelationship.
Law's Stoning vs. Grace's Liberty
Les contrasts the law's command of death by stoning for Sabbath work with grace, showing believers are no longer under that legal demand.
Two Totally Contrary Principles
Les states law and grace are two totally contrary principles and that Paul continually cries against legalism in any form.
Grace Is Not License
Les shows Paul's own question—shall we sin because we are not under law but under grace?—and answers 'God forbid,' clarifying grace does not give license.
Yoke of Bondage Is Legalism
Les identifies the yoke of bondage in Galatians 5:1 as legalism and connects it to the Judaizers' pressure to return to circumcision and the law.
Galatians 4:28: Now we, brethren, as Isaac was, are the children of promise.
Paul identifies believers with Isaac, the child of promise, rather than with Ishmael, the child of the bondwoman.
Galatians 4:30: Nevertheless what saith the scripture? Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the free woman.
This is the verse Paul applies to show that law and legalism must be cast out, not retained alongside grace.
Galatians 5:1: Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage.
This verse commands believers to remain in Christ's liberty and avoid the bondage of legalism.
Romans 6:15: What then? shall we sin, because we are not under the law, but under grace? God forbid.
Paul answers the objection that grace gives license to sin, showing it does not.
Les Feldick identifies the yoke of bondage as legalism. Paul commands believers to stand fast in Christ's liberty and not be entangled again with legalistic demands such as the Judaizers were imposing.
No. Les emphasizes that God did not tell Abraham to give Ishmael a separate tent next door. He said to cast out the bondwoman and her son, picturing the complete separation of law from grace.
No. Paul asks, 'Shall we sin, because we are not under the law, but under grace?' and answers 'God forbid.' Les explains that being under grace does not mean we are free to sin; it means we are free from the yoke of legalism.
Watch the Teaching: Why Mixing Law and Grace Cancels the Work of the Cross