But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us.
Romans 5:8
Don't base your worth on your own thoughts or feelings. Learn to see yourself as God sees you. Jesus' sacrificial death attested to this truth: You are acceptable to God and accepted by God. You are acceptable to God because Christ took away your sin and gave you a new beginning with Him. You were accepted by God long before creation when He intended for you to be the object of His love.
Never lose sight of God's unwavering love and acceptance. The gospel teaches us that long before you even consider making peace with God, He has already gone ahead and made you right with Him.
Your salvation is secure because of the accomplishment of Christ’s finished work on the Cross. God offers you two precious and priceless gifts through Jesus' perfect sacrifice that allows you to be right with Him. You have God's gift of forgiveness for all your sins as well as God's gift of perfect righteousness. Both gifts give you a clear conscience and the confidence to live guilt-free.
How can we be certain?
Because God's divine nature is absolutely pure and holy, He cannot tolerate sin or ignore it. Your "old you" were so full of sin and fell so far short of God's glory that unless God made a "new you" in Christ, you would have incited His divine wrath and judgement (Romans 2:5).
Christ cannot make you a new creation unless the old creation is removed from you first. You are liberated from your "old you" by being crucified with Him, allowing you to live in your "new you." In other words, you are no longer the person you were before you met Christ. You are a completely different person now that you believe in Him. God sends His Holy Spirit to dwell within you, teaching you how to live as a new creation in Christ. If you trust His leading, you will not fail or falter.