John 3 tells us very plainly that if we want to have eternal life, we must trust in Jesus Christ alone for salvation. God gave His Son so that those who believe in Him will have eternal life (v. 16). Those who believe in Christ are not under condemnation, but those who refuse to believe are condemned already and the wrath of God abides on them (vv. 18–36).
There is no doubt that we must believe in Jesus to be saved. However, many Christians do experience doubt over whether they have actually believed in Jesus. So that we may consider the question of how we know if we are truly believers in Christ, we will now take a break from our studies in John and use Dr. R.C. Sproul’s teaching series Assurance of Salvation as our guide for this important topic.
When we consider the matter of assurance, it is clear that believers have a certain duty to work toward attaining certainty about their salvation. Scripture explicitly commands this; for example, 2 Peter 1:10 instructs us to be diligent to confirm our “calling and election.” Yet there are many ways in which God’s Word implicitly exhorts us to pursue assurance as well. Consider the parable of the sower, for example. Among other things, this parable tells us that it is possible to profess faith in the gospel and yet lack the true faith that perseveres and produces a harvest of spiritual fruit. Many who hear the Word of God appear to be converted, but later they fall away because the gospel never truly took root in their souls (Mark 13:1–20). That should encourage all of us to seek to know whether we are good soil, whether we have truly been saved and will persevere to the end. We cannot assume that we are good soil simply because we have confessed faith; we must search our hearts and our lives to be certain that we are not poor soil or that we will not be overcome by the thorns and thistles of life.
Throughout church history, many people have thought that God does not really want us to be certain of our salvation, that gaining true assurance would make us complacent in doing good works in service to the Lord and our neighbor. Scripture, however, wants us to be sure of our salvation. The entire epistle of 1 John, for example, was written so that we would know that we are saved (5:13). Thus, we should eagerly pursue the assurance of our salvation and seek to know if we are truly in Christ. Indeed, pursuing assurance is part of our Christian duty.