Regardless of the overwhelming imagery of your past life, you must determine to refuse the enemy any access whatsoever into your mind, to torment you about what God has already cleansed and to undermine your desire to trust that once you believe in the LORD Jesus in your heart and confess it with your mouth, you are saved (John 1:12, Romans 10:9-11). Let God be true and all men liars, including the devil, the father of those who remain lairs (Romans 3:4, John 8:44).
He says, “As far as the east is from the west, so far hath he removed our transgressions from us.” (Psalm 103:12). Do you know how far it is? How can you ever imagine that God’s work is incomplete because of your remembrance of your past and the constant temptation yielding to contemplation to rekindle old ways? All that, as vivid as they may be to you, have nothing to do with the finality and faultlessness of the New Life you have received in Christ Jesus. The same way you have BELIEVED to be saved in the first place, is the same way you need to keep BELIEVING to CONTINUE in your newness of life.
…that He died and has resurrected…
Now, you don’t actually need to be transported to heaven to confirm with God or check it out before you can be sure (Romans 10:6) neither do you need a visit to hell to verify the truth of Christ’s resurrection (Romans 10:7). All that you need to do is believe and you CANNOT be ashamed (Romans 10:11). That means God who promised is faithful to keep His word and regardless of the attack of the enemy on your mind and your spirit man, let God be true and all men liars, even the devil. (Psalm 119:89-90, Hebrews 6:16-19)
 For ever, O Lord , thy word is settled in heaven.  Thy faithfulness is unto all generations: thou hast established the earth, and it abideth.
Psalm 119:89-90 KJV
“God also bound himself with an oath, so that those he promised to help would be perfectly sure and never need to wonder whether he might change his plans. He has given us both his promise and his oath, two things we can completely count on, for it is impossible for God to tell a lie. Now all those who flee to him to save them can take new courage when they hear such assurances from God.”
Hebrews 6:17-18 The Living Bible
…to save you.
What we are dealing with here is assurance of salvation. The devil fiercely tries to sell you a lie (and he is the perfect conman) to permanently break down the desire to turn to the LORD and follow Him. By giving you an impression that you are not (yet) saved due to strong imagery of your undesirable past, he makes you to forfeit what God has said and you know, agreeing with the devil is all that is needed to thwart your faith or new life in Christ. So the question is whom to agree with. Christ or satan? You do NOT need any extra grace than what heaven releases to everyone who is turning to Christ …to believe simply that you are entirely saved by the righteousness of God in Christ Jesus and not by any act of righteousness you have done yet.
The trick is this. Those who will believe this simply, like a child, will walk into the newness of life that manifests in a changed life full of good works. And those who don’t believe, thinking they must do something else first, by the way of a good work, will never be able to experience the fullness of the life of Jesus in them. They are seeking to gain the new life by their works rather than seizing from it and entering into the works of God, which brings into the promised rest, resonating with divine assurances of salvation.
Now, let’s deal with those satanic arguments and sinful imageries of the past. Please read 2 Corinthians 10:3-6. Then let’s read 4 & 5 again in KJV & The Living Bible
(For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds;)  Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ; 2 Corinthians 10:4-5 KJV
“I use God’s mighty weapons, not those made by men, to knock down the devil’s strongholds. These weapons can break down every proud argument against God and every wall that can be built to keep men from finding him. With these weapons I can capture rebels and bring them back to God and change them into men whose hearts’ desire is obedience to Christ.” 2 Corinthians 10:4-5 TLB
Take time and let this soak into your spirit. This stronghold of lack of assurance is a lie and argument that the devil is sponsoring into your life by your own constant contemplation and dissatisfaction about your past life, friends, activities and objects that serve as constant reminders of this and any direct spiritual assault of satan against your mind to discredit your newfound faith in Christ. There is one truth I must tell you and the devil will do anything to keep you from knowing, understanding and accepting (believing) it. It is that, when you believe in your heart and confess with your mouth the LORD Jesus as I said initially (of course having confessed and repented of your sins – Matthew 3:2, Luke 3:8), you are instantly justified – “just-as-if-I’d-never-sinned”.
All those sins the devil is reminding you of is actually illegal, it is illegal for him to do that, because all your sins and the curse of it has been blotted out and nailed to the cross of Christ (Please read Colossians 1:13-15). That is the way God sees you now but the devil will want to force his lies on you; remember that he can hardly tell the truth, he is the father of liars (John 8:44). So, whose report will you believe?
Believing what God says about Himself and your new life in Christ is one major weapon of your warfare to destroy all of satan’s arguments in your heart. This is using the word of God, which is your sword in dealing with the devil. Swinging your sword at him is basically presenting evidence of your new position in Christ. When you confront him with God’s Word, you are submit(ing) yourself to God and resist(ing) the devil, and he MUST flee from you (James 4:7).
Now, come to the LORD afresh and tell Him you are sorry for doubting His work. And then cast yourself upon Him. Tell Jesus that “You are my Saviour, I cast all my sins upon You and I do away with my sinful nature.” Believe in your heart that the LORD Jesus was raised from the dead and confess it with your mouth that He is now LORD (owner, master) over your life, and guess what? You SHALL be saved (Romans 10:8-9).
Photo credits: Creation outreach, Evangelical outreach, pastorbillholdridge dot wordpress dot com, Charles Lewis