Assurance of salvation is a precious gift that is provided to those who believe the Gospel. But what if we do not have assurance of salvation? Are we living in sin if we do not have assurance? Is assurance even something that Christians should seek?
We will attempt to answer these questions, first, by giving a biblical definition of Assurance, then by reasoning from the Biblical testimony whether or not lack of assurance is a sin, and if it should be sought after.
The Gospel is the good news of Jesus' death, burial, resurrection and ascension on the behalf of sinful man for the glory of the Father. (I Corinthians 15:1-8) The conditions that are prescribed for identification with what Christ has done on our behalf are faith and repentance, or, conversion. (Mark 1:15) Implicit in conversion is the assurance of our salvation. If I really believe that Christ died on my behalf, as my substitute, then I should be assured that His work is enough. Assurance in this sense is being assured of what Christ has done.
Secondly, assurance of salvation comes from the regenerating work of the Holy Spirit. Jesus told Nicodemus that he must be born again before he could see the kingdom of God. (John 3:3)
Part of assurance of salvation then, is the work of the Spirit that allows us to see God's kingdom. Not with physical eyes but with those of faith. Then the Spirit's continuing work in us produces a yearning in us to cry out to our heavenly Father. (Romans 8:14-17)
Finally, this continuing work of the Spirit in sanctification causes spiritual growth by which we see evidences that we are children of God. (Romans 8:14) Those who are truly saved see evidences of their salvation. The Apostle John in I John gives many tests by which we may know that we 'know God'. If we keep His commandments, love our brother, confess the Son, practice righteousness, look for His return, walk in deed and truth, believe in Jesus Christ, heed the Apostles teaching, abide in love, walk in the light, and love God, to name just a few, then we know that we have been born of God.
All of these evidences can be boiled down to two questions; Am I believing?, and, Am I repenting?
Is assurance of salvation a requirement for salvation? No. John Bunyan wrestled with his salvation for a long period of time. He thought that he had committed the unpardonable sin. But he sought after God and finally was assured of his salvation. Read Grace Abounding by Bunyan if you ever have the opportunity. Assurance of salvation is not a condition for salvation. Assurance is implied in conversion, as I said before, but a Christian may not see the implication.
Is lack of assurance a sin? I think in most cases lack of assurance is a lack of information. They have not been taught that a person actually can have assurance. They think that if they believe in Christ and hope for the best everything will work out. But this is not a Biblical hope. Hope in modern usage means 'a wish for something that may or may not happen'. Biblical hope means 'looking forward to a certain outcome'. Our great hope is the certain return of Christ and the redemption of our bodies. This is a certain outcome for those who believe in Christ and repent of their sins. So if a person believes and repents, and later has doubts, does this mean that they are sinning? No. It means that they are missing out on a tremendous blessing that we have in this life.
It is apparent then that assurance is something that should be sought after. Lack of assurance should be repented of. That might not make sense, since I just said that lack of assurance is not sin. Repentance is a turn from one thing to another thing. Repentance in this case would be turning from lack of knowledge and assurance in order to seek knowledge and assurance in God. Search the Scripture. Pray to God. Examine yourself.
You will find one of two things. Either you are not saved and have nothing to be assured of, or, you will find assurance of salvation. If you find the first, repent and believe the Gospel. If you find the second, rejoice in God's blessing of assurance.