/ heart / Warren Peel

Following up on a Spiritual MRI of the Heart

A month ago I wrote about how to carry out a spiritual MRI of our hearts. Let’s assume you’ve done that and you now have the results. Now what? The answer is not some esoteric secret available only to an initiated few. It’s the ABC of Christian living. The treatment is repentance and faith, and we’re to do both with all our hearts.


Repenting with all the heart means repenting with our minds, affections and wills. The Westminster Shorter Catechism spells this out very clearly in question 87: What is repentance unto life? Repentance unto life is a saving grace, whereby a sinner, out of a true sense of his sin, and apprehension of the mercy of God in Christ, doth, with grief and hatred of his sin, turn from it unto God, with full purpose of, and endeavour after, new obedience.

1. The Mind. (‘…out of a true sense of his sin, and apprehension of the mercy of God in Christ…’). The first step in repentance is to recognise our sin as it truly is and to confess it to the Lord and to those we have sinned against. It means calling it what it really is—an offence against the holy God. We don’t dress it up, we don’t excuse it or mitigate it. We see it in all its horrible ugliness and own it before God.

2. The Affections. (‘…with grief and hatred of his sin…’) True repentance is never just a mental activity. It’s not enough to recognise that we have sinned or describe our sins with biblical accuracy. We don’t look on our sins with clinical detachment, as if we’re observing a nasty virus under a microscope. Our knowledge of our sin should grieve us in the depths of our souls. But even this isn’t enough. A final decisive element is essential.

3. The Will. (‘Repentance unto life is a saving grace, whereby a sinner… doth… turn from it unto God, with full purpose of, and endeavour after, new obedience.’) True repentance inevitably leads to a U-turn as we turn away fromsin and pursue righteousness. Repentance is never just stoppingdoing what God forbids but doing what God commands. We put off the old self and put on the new. We put sin to death and we make righteousness alive. This reflects the dynamics of Christ’s saving work for sinners—just Jesus Christ died to sin and rose to new life so we die to sin in him and are made alive to righteousness.

So when we find sin in our hearts, by the grace of God we repent of it—we turn from it with grief and hatred and we pursue its opposite instead.


It’s only through faith in the Lord Jesus Christ—by completely relying on him—that we can put to death the sins we find in our hearts and make righteousness grow and flourish. Faith is not just for the beginning of Xtn life, as if God accepts us when we believe but then sends us off to be holy on our own. Our growth in holiness is his work too. Phil 2.13: it is God who works in you, both to will and to work for his good pleasure. What does this look like in practice? We are called to believe with our heart—that is with our mind, affections and will.

1. The Mind. (Theologians call this aspect of faith by the Latin term notitia). There are certain truths we need to know and understand and think about and believe to be true. We can’t believe in what don’t know or have some understanding of. As we repent of the areas in our hearts where we have uncovered sin, we need to believe especially what Scripture says about our great Saviour.

(a) We need to believe in our minds, for example, that Jesus Christ the Son of God is the Saviour of sinners; that he came from heaven to earth to live the life of perfect obedience we can’t live; that he took a true human body and soul—that Jesus had a real human heart and that he guarded it perfectly every moment of every day. In his mind he only ever thought true, accurate thoughts about God, himself and others. He was full of wisdom and discernment. He never once made a wrong judgment about anything. We need to believe that his affections were flawless—that the Lord’s law was his chief delight and that he loved the Lord with all his heart, soul, mind and strength and loved his neighbour as himself. With his willhe obeyed every command of God perfectly—he never once did anything or thought or said or felt anything that was not perfectly good and right. He always did and spoke and thought and felt and desired what was perfectly right. He gladly submitted his will to his Father’s. We need to believe that he kept his heart pure in all the various seasons of his life—when he was slandered and persecuted by his enemies, when sinful men were trying to trap him in his words, when he was exhausted, when he was betrayed and abandoned, when he was overwhelmed with sorrow to the point of death, when he was hanging on cross in unspeakable, unfathomable anguish of soul bearing the full force of the wrath of God against the sins of his people whose guilt he was carrying. That he was tempted in every way, yet without sin. We need to believe that his record of obedience is offered freely to all who trust in him.

(b) We need to believe that Jesus Christ died the death that we deserve. That on the cross all the guilt of our wicked, deceitful hearts was imputed to him—every failure to keep our hearts: every stray thought, every impure fantasy, every sinful longing, every envious feeling, every act and word—all the things we should have thought and felt and desired but didn’t: Jesus Christ took the guilt of it all and atoned for it all by his blood on the cross. God the Father punished his Son as though your heart was his heart.

(c) We need to believe that Jesus Christ rose from the dead, victorious and vindicated, and that he ascended to the right hand of the Father to pour out the Holy Spirit to indwell us and empower us to live for his glory.

These are just a few of the truths we need especially to fix our minds on in faith. But purely mental belief, notitia, isn’t enough.

2. The Affections. We don’t just believe these things are true with our minds (the Devil himself does that); we need to embrace these truths with our affections (the theological term for this element of faith is assensus). As we meditate on these glorious realities, our emotions are stirred and we believe they are true with joy and delight and love and gratitude for the Lord’s mercy and grace. Don’t just give intellectual assent – souls filled w gladness b/c of them. But even this not enough.

3. The Will. Faith that is from the heart doesn’t just carry the mind and the affections but moves the will to trust Jesus Christ and depend on him (theologians call this fiducia). We need to exercise faith in Jesus Christ as Saviour. We need to trust that all the promises God has made are ours in Christ; we need to trust him to take our guilt and give us his righteousness; we need to trust that he has dealt with our guilty hearts and that all our sins are truly forgiven.

It's a little bit like someone who is seriously ill and in need of major surgery. They may have notitia: they believe they are sick and that surgery is their only option. They may have read all there is to read about their condition and this operation and believe that it will cure them. They may believe that the surgeon is qualified and competent to carry out the surgery. They may have assensus: they hate being sick and long to be well; the thought of having the surgery and being healed fills them with joy. But all the notitia and assensus in the world will do them no good whatsoever unless they go into the operating theatre and entrust their life into the hands of the surgeon - only fiducia will save them. Notitia and assensus must come first, but they will not save unless this third and crucial aspect of faith comes into play.

Are you exercising faith in all of its fullness? Do you believe with all your heart? Are you relying on the perfect heart obedience of Jesus Christ? Are you trusting every day that he makes you righteous in God’s sight and never anything we can do? Are you trusting in his power to overcome sin and temptation?

Set your faith especially on Christ’s death—on Jesus as the slain Lamb. The death of sin comes through the death of Christ. He died to destroy the flesh. Whatever temptations you face, Jesus died to destroy them all.

Repentance and faith. This is how we become Christians at conversion and this is how we continue as Christians throughout our lives until the end when we no longer will have any sins to repent of and we will walk by sight not by faith!

Maranatha! Come Lord Jesus!

Warren Peel

Warren Peel

Warren has been married to Ruth since 1998 and God has blessed them with four daughters. He is Pastor of Trinity RPC in Newtownabbey, Northern Ireland. He serves as a Trustee of the Banner of Truth.

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