What is the heart of the matter? Don Henley's song: The Heart of the Matter, says I think it's about forgiveness; And indeed it is, but there are many miss-understandings about forgiveness. For example forgiveness by law is an endless mission impossible many fail to realize. All who tried to attain righteousness (grace) of the law failed to attain it: Romans 9:31. For by law if you don't first forgive all men all tresspasses, then neither are you forgiven; And who knows all the tresspasses of all men, or even those of a spouse or neighbor? Furthermore the only plausible way to forgive all men all tresspases is by abolition of law, since by the curse of the law in Do-teronomy & Don't-eronomy if any try and fail to keep all the law all the time, to a 1000 generations, then all are accursed; And any law imputed sin to anyone also imputes unpardonable sin and a death sting to all. So reconciling the world to that God, in Christ (is the end of the law), does not law impute (unpardonable) sin, as is noted in 2Corinthians 5:19. God hath forgiven you, and notably for Christ's sake in Ephesians 4:32, is not by you first forgiving all men as required for getting forgiven in Matthew 6:15; But rather by the abolition of law: Christ is the end of the law: Romans 10:4. For as Paul notes, Christ died (to the law) for you while you were yet a sinner by law, which makes sinners all, none righteous, no, not one. So you are forgiven by God & Son, but it's notably by abolition of law, not by you being law abiding to deserve forgiveness, which is a mission impossible. Furthermore, the reason biblical charity "never fails", is because "charity thinketh no evil(law)" to even forgive: 1Corinthians 13. Charity is to be put on "above" forgiving one another, not to offend and forgive one another. So biblical charity is neither of two law loves, but rather perfect love, which is pure grace.

What is the heart of the matter? It is what comes out of our own mouth, and from the heart, that either justfies us or condemns you, makes you either forgiven or unforgiven, as being either with God & Son or against God & Son, as either gathering with or scattering abroad, via either good fruit or corrupt fruit, which is to say grace or law. We find this theme throughout the Bible. For example Job 15:6 says: Thine own mouth condemneth (laweth) thee, and not I. Matthew 12:30-37 notes the words we speak either justify us or condemn us; And such justification or condemnation comes "from the heart": Matthew 12;34; Matthew 15:11-18; Mark 7:18-23; Luke 6:45; Romans 6:17; Ephesians 6:6; Which is further clarified as doing the will of God: I will have mercy[grace], and not sacrifice[law], or not doing the will of God from the heart. Doing the will of God notably precedes receive the promise: Hebrews 10:36; And all who did not do it notably died and received not the promise: Hebrews 11:13,39. For it is written  "If any man defile(law) the temple of God(Grace), him shall God(Law) destroy; for the temple of God is holy, which [temple] ye are": 1Corinthians 3:17. In short, law self-destructs; So if your heart be troubled(lawed), it will attack and defile itself with it's own mouth. So we are told make straight paths for our feet: grace-->mercy-->peace, and "follow after peace", not go after them left or them right (Luke 17:23; 21:8) who go to OT Law or NT Law; Lest any root of bitterness springing up trouble [you], and thereby many be defiled: Hebrews 12. Blessing(grace) and cursing(law) coming out the same mouth ought not so to be: James 3:10; Since both blessed(graced) + cursed(lawed) = "accursed": Galatians 1:8,9. So if any man, or even any angel(minister, star, messenger) bring you such, let him (not you) be accursed. In short: take heed that no man deceive (law) you, which would include the man Christ Jesus, which is mirrorly reverse of Jesus Christ by whom came grace and truth;  Not grace and law, which would be as life and death = dead end = extinction, not salvation.

For the only foundation laid to build on is "Jesus Christ": Mt 1:1 ... 1Cor 3:11 ... Rev 22:21, "the same" yesterday, to day, and for ever: Hebrews 13:8; And it is further clarified that both peace with God and eternal salvation are notably "through Jesus --> Christ", only "in Christ" thereof. For Jesus did not give them rest (peace); but rather division and not peace. Jesus took Noahic grace + law and made it either grace or law (division, not peace): life or death; And Christ took grace or law and made it grace (peace, not divided), by abolishing the law(the enmity: Eph 2:15), to bring an end to all the law vs law and law vs grace divisions required to get to the heart of the matter: Christ is the end of the law: Romans 10:4, and not the mend of law: Mark 2:22; Luke 5:36,37. God is the author of peace, not of confusion. God is the author of grace, not grace and law, which cannot co-exist in peace, since they are contrary things, as contrary as bless or curse, with or against, gather or scatter, good or corrupt, justify or condemn, life or death: the contrary part notably being the law: the enmity: what's "against" us: Colossians 2:14, the part to be done away, to end the part-iality. For when perfect-ion comes, as what's best for all, then part-iality is done away: 1Corinthians 13:10; Which is also to say when better blessed man kind, childish things (laws, sacrifices, divisions, cover ups, wars, famines, earthquakes, troubles, sorrows) are put away: 1Corinthians 13:11. Such are childish things of being made one proselyte: more the CHILD of hell(law) than other hypocrites, fools, blind guides, and vipers in Matthew 23, where it's noted such like sat in Moses's Seat: Law. The judgment seat of Christ is not law(unjust), but rather grace(just); Not unrighteous judgment nor vengeance of an unjust judge, but righteous judgment (grace) and mercy upon all; Not sinners all by which all perish, but sinners none by which none perish. For sin is not imputed when there is no law, and Christ is the end of the law. Where and when no law, there and then no accusation, nor condemnation, nor concupiscence, nor transgression, nor tresspass, nor wrath, nor death sting of sin (which law is both the source and strength of).

What is the heart of the matter? What can trouble the heart to the point it defiles, condemns, attacks others and thereby condemns itself with it's own mouth? When looking at verses talking about trouble(s), troubled, and troubled water, we find the root source of the trouble (agitation to<-->fro, disturbing equanimity, disqueting, striking one with fear and dread, perplexing the mind with scrupples and doubts, etc) is the law; or our own legalism. For a heart established with grace neither tempts nor can be tempted: neither laws nor can be lawed: neither troubles others nor can be troubled. For by grace is sufficient (no law required) all things work out for good only, not both good and evil.

The word of God gets to the heart of the matter in Hebrews 4, where it also notes Jesus did not give them rest. It does so by dividing asunder soul<-->spirit, as with Adam1<-->Adam2 in 1Corinthians 15:45. Then because "as in Adam all die", the word of God also divides asunder joints<-->marrow, which is to allegory say rightly divided laws<-->grace; And notably to discern the thoughts and intents of the heart. For what comes out the mouth can either justify or condemn a person, and what comes out the mouth comes from the heart. So let not your heart be troubled (lawed), lest it condemn (law) you with your own mouth. Rather let your heart be established with grace, so it will justify (grace) you with your own mouth.

To establish a heart "with" grace (not both with and against), law has to become dead testator of the New Testament so grace may be of force; Since law makes grace "no more grace" and Christ of "no effect": Galatians 5:4. As grace became dead testator of the Old Testament so law could be of force, Law is to become dead testator of the New Testament so grace may be of force; And notably in a manner that's not adultery (claiming to be espoused to one: grace and found whoring with another: law), as explained by Paul The Apostle: Romans 7:2-6 and Hebrews 9:16,17. So reckon yourself dead to law to become alive unto God(Grace).

For it's not both first and last, lest the last state of man be worse; Not both before and after, lest it be destroyed afterward as Jude 1:5 notes happened to all the Exodus people. It's not both old and new: Mark 2:22, lest new wine in old bottles causes "burst": Luke 5:36,37, as notably happened to Judas: Acts 1:18. It's not both child and man in "Let us make man": Genesis 1:26, nor both child and man in "when I became a man I put away childish": 1Corinthians 13:11, nor both child and man in "blessed the man to whom the Lord will not impute sin": Romans 4:8. So adults who pride themselves on being children of God are told "be no more children": Ephesians 4. It's not both condemned and justified by law and grace, not both extinction(all perish) and salvation(none perish), which would translate into a global oxymoron like one proselyte who's both dead and alive, both cold and hot = lukewarm, which won't do, as noted in Revelation 3:16. Rather it's either or: either justified or condemned, and by your own mouth from your own heart.

The grace of our Lord Jesus Christ with you all. Amen.