Are you confident that you are saved, that you have received God’s grace in Christ, and that you will forever enjoy God’s presence in heaven? Christians sometimes wrestle with the assurance of their salvation, however, God intends His beloved children to walk by faith in the joy and comfort of real assurance. I want you to have the joy of real assurance.
Whenever you doubt your salvation, you should look to Christ in true faith believing the promises of God and resting in the security of Christ’s merits credited to you. Through faith, all the perfections of Christ belong to you. Too often, we look to ourselves expecting to find goodness that is only in Christ, and our assurance wanes. Of course, we acknowledge and grieve our ongoing battle with our sinful flesh, rightfully so, but sometimes the battle distresses us so much we suffer uncertainty as to the eternal state of our soul. How can I be saved if I act like this? We must realize that our future perfection is not yet, but one day will be. Jesus is still transforming us. Therefore, by looking to Christ in true faith in our weakness and struggle, we can draw confidence and assurance from our union with him who is our righteousness, holiness, and goodness. It is an inseparable union with Christ through faith that calms our uncertain and worried souls.
But there are hypocrites alongside true believers in the Church. These hypocrites seem very confident and assured that they are saved, that heaven is their eternal home, yet they do not look to Christ in true faith but instead look to themselves and their own perceived goodness, they do not humbly grieve and repent of their sins, nor do they produce the true fruit of faith in good works that glorify God and benefit others. Hypocrites should not be confident at all, they should be unnerved. But this is their problem; they are confident when they should be unnerved.
Westminster Shorter Catechism 35 asks, “What is sanctification?” Sanctification is important to define and understand, because it relates to the assurance of our salvation. Christ is our assurance. His merits are our confidence. But how do we know that we have truly received Christ? Well, if we have truly received Christ through faith and are truly united to him, his grace and Spirit will be visible in our sanctification. Without sanctification, we cannot be assured or confident that we are truly saved. Sanctification is a necessary consequence of truly receiving Christ by grace alone through faith alone. Westminster Shorter Catechism defines sanctification like this:
Sanctification is the work of God’s free grace, by which we are renewed in the whole man after the image of God, and are enabled more and more to die to sin and live to righteousness. 
This short and profound statement can help us find greater assurance in Christ.
First, notice that sanctification is a work of God’s free grace. Second Thessalonians 2:13 says that sanctification is “by the Spirit.” God graciously sanctifies us, and when He does, it assures and comforts us that we are indeed saved because God’s grace is active in us.
Second, sanctification is our renewal after the image of God. In Ephesians 4:23-24, Paul writes, “and to be renewed in the spirit of your minds, and to put on the new self, created after the likeness of God in true righteousness and holiness.” When renewal happens in us and we grow in righteousness and holiness, grow in obedience to God, it is evidence of God’s grace transforming us.
Third, sanctification is the Holy Spirit enabling or empowering us to put sin to death and to joyfully obey God’s law. This is a very important point to understand if you are to have the assurance of salvation. Paul writes in Galatians 5:24, “And those who belong to Christ Jesus have crucified the flesh with its passions and desires.” You are dead to sin. Paul also says in Romans 8:13–14, “For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live. For all who are led by the Spirit of God are sons of God.” So as the Holy Spirit leads and empowers you to fight sin, to put to death the deeds of the body, as you more and more hate, grieve, and flee sin, your spiritual progress testifies to your salvation in Christ. Hypocrites are either concerned about their sin for self-righteous reasons or not at all. Hypocrites act out of love for self or the fear of being condemned (BC 24). Believers, on the other hand, grieve their sin because it displeases their Lord whom they love; their godly grief leads them to repentance and obedience as does God’s kindness (2 Cor. 7:9-10; Rom. 2:4). Believers act out of love for God and others because they are not condemned.
Heidelberg Catechism 86 says that believers “may be assured of [their] faith by its fruit.” Assurance of salvation can be strengthened each time we have a victory over sin and make progress in sanctification. Each victory, each step ahead in sanctification, is God graciously producing fruit in us. Evidence of God’s grace assures. An increased appetite for God’s Word and corporate worship assures. Escalating hatred of and grief over sin assures. Deepening love for the Church assures. Where do you see the Spirit conforming you to Christ? There is assurance for you. Our brothers and sisters should see our progress too, and their encouragement can also excite greater assurance.
Let us look to Christ together to find our assurance in his person and ongoing ministry to us, and let us celebrate his work of grace in us. Let us say no to sin and yes to righteousness and then celebrate our no and yes as God’s kind and helpful mercy and grace to us. Let us draw comfort from God’s ongoing gracious work of making us like Jesus.
 The Confessions of Our Faith, Fortress Edition, ed. Rev. Brian W. Kinney (Fortress Book Service & Publishers, 2007), 129.https://www.tanglewoodpublishing.org/