I was fortunate to have been raised in a two-parent family. I had a great Dad. I had what today would be considered an “old school” upbringing. Mom did most (maybe all) of the spanking but Dad made his presence felt. There was the potential of feeling Dad’s belt. When I was quite young he convinced me that it was a bad idea to lie to him. Nevertheless, I never doubted that Dad loved us, that he was completely committed to taking care of us, and that he would protect us. It never occurred to me to juxtapose discipline and love. I think all of us children knew that Dad did and said what he did because he loved us. As I grew up it was helpful to know where the boundaries were. It was helpful to be able to say, “Nope. Can’t do it. Dad will (metaphorically) kill me.” The greater fear, of course, was disappointing him.

Sonship In Hebrews 12
According to Hebrews 12, Christians, i.e., those who have received, by grace alone, through faith alone, the benefits of the covenant of grace, are motivated to sanctification not by the covenant of works (“do this and live”) but by the covenant of grace (“do this because Christ lived for you”). Christ is, in the first instance, our obedient substitute. He did for us what we would not and could not do for ourselves. By God’s free grace (sola gratia) to us sinners his perfect righteousness is credited to us and received sola fide. In the covenant of grace, however, Christ does become our pattern, in certain respects. We want always to be careful not to turn Christ into a “model believer.” That path leads right back to Pelagius. Do not be misled: Jesus is the Savior and we are the saved. Nevertheless, having observed the vitally important differences between Christ’s faith and ours, we do look to him as the “looking to Jesus, the founder and perfecter of our faith, who for the joy that was set before him endured the cross, despising the shame, and cis seated at the right hand of the throne of God” (Heb 12:2. See also 2:10). We ought not to grow weary because, unlike Jesus, in our struggle against sin we have not yet shed blood (Heb 12:3–4).

Unlike some (e.g., the Remonstrants, Richard Baxter et al), the pastor to the Jewish Christians, who were tempted to return to the types and shadows, did not put his congregation back under the covenant of works for salvation (justification, sanctification, and deliverance from the wrath to come). He quoted Proverbs 3:11–12 to show that, when we suffer for the Lord, we are not unloved but loved. We are adopted sons and as such we endure God’s fatherly discipline (Heb 12:7) because fathers discipline those whom they love (v. 8).

Ursinus On Filial Vs Servile Fear
It was in light of this passage and the whole sweep of the history of redemption, in which the Lord consistently manifested his fatherly kindness to his people, that Zacharias Ursinus (1534–83), under Heidelberg 94, distinguished between two kinds of fear: servile and filial. This distinction is essential to a sound grasp of what John Stott called “Basic Christianity.” Believers should not have a servile fear of God. Believers ought to have a filial fear of God. The difference is between the covenants of works and grace. Everyone under the covenant of works, after the fall, can only have a servile fear of God. Those for whom Christ has fulfilled the covenant of works are, sola gratia, in a covenant of grace in which the wrath of God has been extinguished for us by Christ, in which the Spirit is graciously and gradually conforming us to the image of Christ, and in which we look forward with joy and not fear to Christ’s return and the coming vindication. It is so important to understand the warning passages in light of this distinction.

Ursinus explained the difference:

Servile fear, such as the slave has for his master, which consists in fleeing punishment without faith and without a desire and purpose of changing the life, being accompanied with despair, flight and separation from God—such a servile fear differs greatly from that which is filial. 1. Filial fear arises from confidence and love to God; that which is servile arises from a knowledge and conviction of sin, and from a sense of the judgment and displeasure of God. 2. Filial fear does not turn away from God, but hates sin above every thing else, and fears to offend God: servile fear is a flight and hatred, not of sin, but of punishment and of the divine judgment, and so of God himself. 3. Filial fear is connected with the certainty of salvation and of eternal life: servile fear is a fear and expectation of eternal condemnation and rejection of God, and is great in proportion to the doubt and despair which it entertains of the grace and mercy of God. This is the fear of devils and wicked men, and is the commencement of eternal death, which the ungodly experience already in this life. “I heard thy voice in the garden and I was afraid.” “The devils believe and tremble.” (Gen. 3:10. James 2:19; Zacharias Ursinus, The Commentary of Dr. Zacharias Ursinus on the Heidelberg Catechism, trans. G. W. Williard (Cincinnati, OH: Elm Street Printing Company, 1888), 514.)

Servile fear arises from fear of judgment. Filial fear arises from God’s grace and love. The latter draws us closer to God and the former (servile fear) drives us away. It, servile fear, is signal of reprobation. Filial fear is a work of God’s grace in our hearts, it reinforces and rests upon God’s gracious promises to us in Christ.

Canons Of Dort 1.16 On The Covenant Of Grace And Filial Obedience
This was not simply Ursinus’ personal opinion. This is the confession of the Reformed churches. At the Synod of Dort, the Reformed Churches of Great Britain, the Netherlands, Zürich, Bremen, the Palatinate et al gathered to confront the Pelagianizing errors contained in the Remonstrance (1610) and in the theology of Jacob Arminius (d. 1609). The Remonstrants complained (that’s what Remonstrants do) that Reformed theology did not produce sufficient sanctity. They wanted more and they wanted it now. In response the Reformed Churches confessed our natural inability after the fall, God’s eternal, unconditional grace to the elect in Christ, and they also reaffirmed the doctrine of the mystery of reprobation. One aspect of God’s eternal decree is to allow those who have fallen to remain in their sin, to act according to their nature. God, we confess, “has decreed to leave in the common misery into which they have willfully plunged themselves, and not to bestow upon them saving faith and the grace of conversion; but, permitting them in His just judgment to follow their own ways…” (Canons 1.15).

The prospect, however, of the reprobation and condemnation of some, should not be a cause of servile fear to believers. We are not reprobate. How do we know? Because we believe. This is what we confess. God has given to us a “living faith” (vivam fidem), in Christ, and a “certain confidence of heart” (certam cordis fiduciam), “peace of conscience” (pacem conscientiæ), which produces in us “a zeal for filial obedience” (studium filialis obedientiæ) that causes us to glory not in our cooperation with “assisting grace” (that was the language of the Remonstrants) but in God’s unconditional salvation received sola gratia, sola fide. Even when our experience (sentiunt) wanes, we make use of the divinely ordained means (mediis) of grace and trust that, through them, our gracious, loving heavenly Father has promised (promisit) to renew in us a sense of his presence. Thus, we do not tremble when someone mentions reprobation nor do we assume that, because we sin, we are reprobates. As God’s adopted Sons, in Christ, we “persevere diligently in the use” of the means of grace (usu mediorum diligenter pergere) expecting the Spirit to encourage us (Canons, 1.16). In the Reformed theology, piety, and practice we do not set the ends (soli Deo gloria), grace (sola gratia), the means (media gratiae), true faith, and consequent obedience against each other. They are complementary.

Conclusion
Because we sin believers are often tempted to discouragement and even to depression. We are tempted to think of God chiefly as a judge and to put ourselves back on a works footing—as if God’s grace was so powerless that we could fall away by our puny efforts. We are tempted to turn inward and to try to “pull ourselves up by our bootstraps.” Such a response to sin and discouragement is a trap. The path to assurance and piety does not lie inward but outward. We must go to outside ourselves to Christ and to his promises. There we find real help. Our bootstraps cannot save us. Only Christ can save us. We fall into doubt and depression because we sin, yes, but also because we do not distinguish between servile and filial fear and because we turn (were it possible) the covenant of grace into a covenant of works. Let us continue to struggle against sin and toward filial obedience. Let us repent daily and, by God’s grace, seek to mortify sin and to be vivified by the Spirit only because of grace and only in a covenant of grace as adopted sons and not as children of wrath.