Chapter 17.3

iii. Nevertheless, they may, through the temptations of Satan and of the world, the prevalency of corruption remaining in them, and the neglect of the means of their preservation, fall into grievous sins; and, for a time, continue therein: whereby they incur God's displeasure, and grieve His Holy Spirit, come to be deprived of some measure of their graces and comforts, have their hearts hardened, and their consciences wounded, hurt and scandalize others, and bring temporal judgments upon themselves.
When John Bunyan took the readers of his allegory into the House of the Interpreter, he gave them two vivid pictures of perseverance. One was a picture of sovereign grace. A man stood by a fire, pouring water upon it as the devil pours temptations on our faith--but the fire burned hotter and higher. Hidden behind the wall, another person stood pouring oil into the fire, as Christ works secretly by the Spirit to preserve the Christian's faith. 

However, Bunyan's other picture depicted personal combat. Many people stood outside a beautiful palace, wanting to go in but unwilling to face the fierce soldiers who stood in their way. One brave man put on armor and attacked them. They hurt him with many wounds, but he fought his way through them and was welcomed into the palace with the words, "Come in, come in; eternal glory thou shalt win." Grace-empowered perseverance is war.

In the first two sections of the seventeenth chapter of the Westminster Confession of Faith, we have seen the promise and the grounds of perseverance. The third section of WCF 17 cautions us to maintain the watchfulness of perseverance. Believers must fight a war on three fronts: the world, the flesh, and the devil. Soldiers on the frontline must always be alert, and how much more soldiers with invisible enemies! 

The Confession warns believers against "the neglect of the means of their preservation." God works through means, and failing to use the means will have serious consequences. Disdaining the means of grace over the long term reveals an unconverted heart. Hebrews 3:12 warns, "Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God." As for the true saints of God, they will repent and persevere, but careless walking may lead them into sad and horrible sins that will cost them dearly before they reach heaven. Therefore, the Scriptures call us to watch and pray (Matt. 26:41; Eph. 6:18).
The Westminster divines list seven weighty consequences that may fall upon believers if they backslide into spiritual lethargy and disobedience.

First, they may experience God's fatherly anger. God will not come against believers in holy wrath and fury, for they have a heavenly Advocate (1 John 2:1). But the Father has not ceased to be holy. His children should fear to displease Him more than they fear anything else (1 Peter 1:15-17). They should fear His frown and rebuke, and seek His smile and reward (Matt. 6:1). 

Second, they may grieve the Holy Spirit. Everywhere a believer goes, he carries in his heart a holy Guest. The Lord within our souls is gracious and loving, but He hates the least sin. Let the Christian not grieve the Spirit (Eph. 4:30), but entertain Him as a good host entertains a welcome and beloved friend. 

Third, they may lose the blessings of the Spirit to some degree. The Spirit produces all their love, joy, peace, patience, and other good fruit (Gal. 5:22-24). Should they grieve this Spirit and risk Him withdrawing some of His gracious influences? 

Fourth, they may harden their hearts. Even believers need regular exhortation or the deceitfulness of sin begins to harden them (Heb. 3:13). They do not benefit as much from the Word because they become foolish and slow to believe all that God has promised (Mark 6:52; Luke 24:25). They may even become instruments of Satan discouraging God's servants and opposing the kingdom of God in some respects (Matt. 16:22-23).

Fifth, they may injure their consciences. Unrepentant sin makes a healthy conscience cry out in protest. Until David confessed his sins, his soul was "roaring all the day long" and God's hand was heavy upon him (Ps. 32:3-5). A good conscience before God and men is a great blessing (Acts 23:1; 24:16).

Sixth, they may do spiritual harm to other people. David's double sin of adultery and murder gave the enemies of God a reason to blaspheme His holy name (2 Sam. 12:14). A faithful life makes the gospel look beautiful, but impurity and rebellion among God's people provokes the world to mock at the Bible (Titus 2:5, 10). 

Seventh, they may suffer the judgments of God upon their earthly life. God forgave David, but He disciplined him by taking away one of his sons and allowing his family to be torn apart with strife (2 Sam. 12:11-14). The Lord sometimes visits sinning Christians with sickness and even death to discipline them (1 Cor. 11:30-34). 
All seven of these considerations call believers to watch against sin and pray for daily grace so that they may persevere in faithfulness. They give us sober reminders that we dare not wave the banner of "once saved, always saved" over a life of rebellion against God. Rather, they call us to a life of faith, repentance, and new obedience, for that is the essence of perseverance.

The perseverance of the saints is a promise to runners in the race of holiness. It is not meant to cradle sleepy sinners in spiritual La-Z-Boy recliners. Therefore, get up out of your sin, fix your eyes upon Jesus, and begin again to run the race set before you with the promise of glory in your hand. 

Dr. Joel Beeke is the President and Professor of Systematic Theology and Homiletics at Puritan Reformed Theological Seminary and pastor of Heritage Netherlands Reformed Congregation in Grand Rapids, Michigan.