In the preface to his new book, “Unlimited Grace: The Heart Chemistry That Frees from Sin and Fuels the Christian Life,” author and pastor Bryan Chapell is upfront about a common concern. When a ministry focuses on the grace of the Gospel, he says, many people quickly do the spiritual math; they reason that “if all we teach is God’s forgiveness of sin, then people will have no incentive to avoid evil.”

We can always respond with John 14:15, Chapell says, where Jesus says to His disciples, “If you love me, you will keep my commandments.” Jesus understood that there’s a “chemistry of the devoted heart,” Chapell says, “and that it’s stronger than the math of the divided mind.”

What we do must not determine who we are, but who we are by God’s grace should determine what we do.

When we fully experience His grace toward us, then our hearts unite with His. His priorities become our greatest joy, and walking with Jesus is no longer a forced march of merit but a willing response of love, gratitude, and thanksgiving. ByFaith spoke with Chapell about a few of the book’s major themes.

In the opening chapter, you introduce the phrase: “chemistry of the heart.” Since this idea is foundational to the book, can you tell us what it means and how it affects our understanding of grace?

The Apostle Paul makes the astounding claim in his letter to the Romans that “where sin increased, grace abounded all the more” (Romans 5:20). You can practically hear his critics howl in response, “Are you, then, saying that we can continue in sin, so that we will get even more grace?” They are simply doing the spiritual math that selfish thinking always encourages: “If God will forgive me later, then why not sin now.” We are always tempted to tally and take advantage of the benefits of sin, if we believe grace will cover us later.

Countering this spiritual math is no easy task. Sometimes we might like to dissuade people from wrongdoing by saying that God will not forgive them later for intentional sin, but we should know this risks contradicting the Gospel. Put whatever caveats you need about sincere and genuine repentance into the equation of experiencing God’s forgiveness, but the biblical answer remains the same: God really will forgive those who truly repent. So what is to keep us obeying God today, when we can bank on His grace for tomorrow?

The biblical answer is not to minimize grace but trumpet it. Paul is not afraid of his critics’ question — he even asks it for them (Romans 6:1). He knows what will counter the spiritual math of selfishness is the heart chemistry of grateful love for God stimulated by apprehension of His super-abounding grace (“super-abounding” is really Paul’s word). This chemistry of the heart is stronger than the math of the mind that reasons for selfish ends. That is why Paul says that “the grace of God … [is] training us to renounce ungodliness and worldly passions, and to live self-controlled, upright, and godly lives in the present age” (Titus 2:11-12). “The love of Christ controls us” (2 Corinthians 5:14), providing new desires, passions, and compulsions that guide and guard Christian conduct.

Love for God is not the only motivation for believers in Scripture. Fear of consequences, desire for reward, longing for affection — all can be appropriate motivations. Still, love for God remains the most essential and powerful of Christian motivations. That is why Jesus makes love for God with all heart, soul, mind, and strength the foundation of our walk with God (Mark 12:30). What stimulates such love? The Bible clearly says, “We love because He first loved us” (1 John 4:19). The reason that the apostles were unafraid of the grace that cascades through Christ’s ministry was that they knew immersing the human heart in such rivers of divine mercy would stimulate loving obedience as no other motivation could.

When you discuss the proper motivation for our behavior, you say we often confuse our “who” and “do.” What do you mean by that? To answer the question “Does God love me?” the reflex response of many is to ask themselves another question: “Well, let’s see. How am I doing?” Whether the person is in a loving relationship with God is determined by how that person is “doing” in terms of meeting God’s standards.

Such a person confuses our “who” and our “do.” Who we are in relationship with God is not determined by what we do; rather, what we do is determined by who we are. That’s why the Apostle Paul encouraged believers in ancient Ephesus, “Be imitators of God, as beloved children” (Ephesians 5:1). The command to imitate God (that is, to be holy as He is holy) is based on the family relationship with Him that His grace has already established. In essence Paul says, “Make who you are determine what you do.” He does not say, “Remember what you do determines who you are’” (see similarly Colossians 3:12ff).The identity God’s grace establishes determines the behavior we imitate. Who we are establishes what we do — and not the reverse!

Grace not only frees us from sin but also provides the fuel of the Christian life.

God’s grace motivates our behavior; our behavior does not manufacture His grace. We live in response to His love, not to qualify for it or to make Him produce it. Our obedience is a prayer of thanksgiving, not a bribe for blessings.

God’s gracious claim on us is our greatest cause for serving Him. His grace does not detract from our devotion but fuels it.

One of my favorite church people I met during the earliest years of my ministry was Maudette. She had been widowed many years, lived alone, and loved flowers. Though her advanced years kept her from tending her garden carefully, it provided a riot of colors and rare varieties that she loved arranging around the platform of our church.

Maudette came to our church only on Sunday evenings. She went to morning services at a church she had attended since she was a child — a church that had sadly drifted from its Gospel moorings. Maudette stayed loyal to that church, hoping that her influence might help the succession of young preachers rediscover the Gospel. But she came to our church in the evenings for what she called her “weekly dose of Bible.”

The difference in the churches was never more evident than at Maudette’s funeral. It was held in her childhood church. Her pastor said a few opening words, praising Maudette’s many years of faithful Sunday school attendance, the had the best decoration and best funeral catering services. Then, it was my turn to read from Scripture, and I read the passages she had chosen about the grace of God for all who trust in Christ.

Next her pastor gave the eulogy, assuring family and friends that Maudette was in heaven because she had attended church so often, was a sweet person, had a beautiful garden, and shared her flowers with the church.

Then I preached the sermon, as Maudette had requested, retelling the Gospel truth that we are saved by grace through faith and not by works (Ephesians 2:8-9). I loved rehearsing how Maudette’s appreciation of her Savior’s unconditional grace had kept her lovingly decorating His house for so many years — even after the stresses of age began to decay hers. But I wanted people to understand the beauty was an expression of her love for Christ, not a payment or bribe to make Him love her more.

My wife later said that attending that funeral was like watching two preachers boxing. One would throw a “goods works” jab; then, the other would throw the “Gospel” punch.

Who won? I don’t know who won that day. I do know that Maudette wanted her loved ones to hear the clear message of the Gospel.

Her hope was not in her flowers but in her Savior. She did not want who she was before God to rest on what she had done in her garden. Fragile flowers are beautiful, but our hope of eternity needs to rest on something far more firm. What we do must not determine who we are, but who we are by God’s grace should determine what we do.

You also talk about how we misunderstand the spiritual disciplines: Pray more, read your Bible more, go to church more. You argue that the only way the disciplines strengthen the Christian life is when we view them as bread, not barter. Can you help us understand that?

What I am suggesting is that many of us need to shift our paradigm of the usefulness of the Christian disciplines (prayer, Bible reading, and the dimensions of Christian sacraments and fellowship). For too many of us, these are a type of Christian barter: We trade our diligence and duty for God’s favor and help. We muster up the effort and discipline to satisfy Him and, then, expect Him to favor us as we wish — our sweat for His sweets.

Such use of the disciplines clearly contradicts Scripture. The problem is not with the disciplines themselves but with our use of them. We are forgetting a very basic biblical premise: The right things for the wrong reasons are wrong.

In the Old Testament, the people of God sometimes offered sacrifices to God as a way of placating Him while ignoring His commands and the suffering of the needy. The sacrifices offered to Jehovah were a good thing in themselves. In fact, God had commanded such sacrifices as a mark of devotion to Him. But when the sacrifices were used to bribe Him, God said that the smoke from the offerings was a stench in His nostrils (Isaiah 1:11-14; Amos 5:12).

If the reason that we read our Bibles is so that God won’t get mad at us or will be nice to us, then we are implicitly trying to buy His goodness with ours. Sometimes people even talk this way without recognizing the attitudes they are revealing: “I knew it was going to be a bad day; I didn’t have a long enough quiet time.”

How long would have been long enough? The thought that we could use the Christian disciplines as a way of plugging faith nickels into the celestial vending machine in the sky falls apart when we remember that our best works are only polluted garments to Him (Isaiah 64:6). We cannot bribe God to bless us.

Our disciplines do not make us acceptable to God because they are never long enough, deep enough, or frequent enough. “Enough” isn’t a measure that works for an infinitely holy God.

The only way that the disciplines function well in the Christian life is when we view them as bread, not barter. They are not trading chips to exchange for God’s grace but, rather, divine manna, providing the nutrition by which our love for Christ thrives. As we meditate upon the lavishness of grace across Scripture, commune with Him in prayer, and experience many dimensions of His mercy among His people, we grow in our understanding of His love. As a consequence, our love for Him grows, displacing lesser loves that attack us even as they attract us.

Only as the disciplines contribute to our love for Christ — the most powerful means of healthy and lasting change — do they serve God’s intended purposes. Those purposes could be compared to the oxygen a marathon runner needs to power through the final miles. Grit, determination, and willpower are also needed but will prove useless if there is no oxygen enabling the effort.

To take in the oxygen they need, runners open their mouths. They do not open wide with the expectation that the effort will manufacture oxygen. No effort of the runners will make more oxygen. They open their mouths to take in the oxygen that already surrounds them. In the same way, we should not open the pages of Scripture, extend our hands in prayer, or reach out to other believers with the expectation that we will manufacture God’s grace to us. His free, unbounded, unconditional grace already surrounds us, ready to be taken in for the strengthening of our understanding of Him and our passion for Him.

To help readers get a firmer grasp on how grace works, you explain that if we truly love Jesus, we love what and whom He loves and that Christ’s priorities become our priorities. Why is that? And how does that help us live with a right understanding of grace?

The transforming power of grace often gets bad press. Efforts to motivate people by telling them how wonderful God’s grace is for them often gets criticized for creating egocentric Christians. The assumption is that too much focus on grace makes people selfish. They get conditioned to think only about their own personal needs (i.e., my need of forgiveness, God’s mercy to me, and the heaven that awaits me).

The concern is certainly legitimate, but the reality is impossible in a heart truly captured by the grace of the Gospel. If we truly love Jesus, then we love whom and what He loves. Whom does Jesus love? He loves the unlovely, the outcast, the needy, the lost, the poor, the orphan, and the widow in distress (Isaiah 16:3-5; Psalms 9:18; Matthew 11:5; John 3:16, 4:35; James 1:27). What does Jesus love? He loves His creation, the creatures of His care, and all those made in His image (Genesis 1:25-31, 2:15; Psalms 145:8-9, 146:6-9). If we love Him, we will love all of these also.

Christ’s grace toward us stimulates our love for Him, which makes us want to do whatever pleases Him by extending His grace toward all that He loves. The consequence is counterintuitive but very powerful.

How is “Unlimited Grace” different from what you have written before?

In this book, I am explaining how grace not only frees us from sin but also provides the fuel of the Christian life. I show people how to find that grace threaded through all the pages of Scripture so that they can mine the gold of the Gospel for themselves from any passage in the Bible without resorting to verbal acrobatics or magic decoder rings.

For many years, pastors have asked me for a simple version of “Christ-Centered Preaching” or “Holiness by Grace” that will help their Sunday school teachers, parents, small-group leaders, and seeking souls find the beauty and power of grace in all Scripture. This is that book!

Bryan Chapell serves as the senior pastor of Grace Presbyterian Church in Peoria, Illinois. He is also president emeritus of Covenant Theological Seminary and the author of several books, including the classic “Holiness by Grace.”

Richard Doster is the editor of byFaith magazine.