Perseverance in anything is not automatic. It certainly does not come automatically in the Christian faith. That’s why there are so many instructions in the Bible about persevering in trials, enduing difficulties, being patient in suffering, running the race, and abiding in Christ. Assurance is not gained by persevering. Persevering in trials by faith is often the result of having assurance. It’s the result of knowing that in Christ I am totally accepted by God (Eph. 1:6).
A lack of assurance is often caused by a misunderstanding of one’s position in Christ. When a person trusts in Christ to save them, he or she receives everlasting life. They have passed from death to life (John 5:24). The very perfect righteousness of Christ is credited to the sinner (II Cor. 5:21). The Holy Spirit immediately seals the believer until the day of redemption (Eph. 4:30). The new believer belongs to God. He has become a child of God (John 1:12). And he or she is kept safe in their new position in Christ (I Peter 1:5; John 10:28). Even a lack of perseverance in faith cannot affect their position as a child of God. Lot, Saul, Solomon, and Demas are examples of saved men who failed to persevere.
Assurance and perseverance are both rooted in the person and work of the Lord Jesus Christ. Although you can suck it up and persevere in the old nature (even unbelievers persevere some immense difficulties), Biblical perseverance is a result of dependence on the power of the Holy Spirit for the strength to endure in faith. It’s not a result of you or me trying to do something for God. If you or I are anxious or fearful or bitter about life’s circumstance, we may be persevering, but we are not persevering in faith. Persevering in faith comes by resting in Him and His word, trusting Him in the moments of time and the circumstances of life. It’s resting in the Lord, trusting in Him for the outcome. It’s learning to be content in whatever state I am (Phil. 4:11). Therefore, “Let us run with endurance the race that is set before us, looking unto Jesus, the author and finisher of our faith” (Heb. 12:2).