In one section of Thomas Goodwin’s book called “A Child of Light Walking in Darkness,” he explains how Satan tricks and deceives a true Christian so that he doubts his salvation. Sometimes Satan will remind us that if a person is a hypocrite, if sin reigns in a person, and if a person is full of self-love, that person is not a Christian. Then Satan says to us: “You played the hypocrite last week and last month. You constantly give in to the sin of anger. You love yourself more than your family and more than God. Therefore you are not a true Christian.”
Notice how this works. Satan uses half-truths to get us to doubt our salvation. It is true that hypocrites, lovers of self, and those who are ruled by sin will not inherit the kingdom of God. However, there’s more to the discussion. A true Christian can stumble into hypocrisy, can give in to sin for a time, and can disobey God by loving self more than Him or others – but this doesn’t mean he is not a true Christian! It just means he’s not yet perfectly sanctified, and that the Spirit in him struggles against the sinful flesh (Gal. 5:17). Satan, the lying deceiver and enemy of Christ and his people, takes our sin, our failings, our stumbling, and our sinful nature and rubs them in our face in order to get us to feel guilty to the point of doubt and despair.
A question comes up: How do we know if the guilt we feel is due to Satan’s conniving or due to the conviction of the Holy Spirit (John 16:8)? Goodwin says that the difference is this: when the Holy Spirit convicts us of our sins He deals “sweetly” with us without putting any “sting” in the conclusion by making us think we’re condemned sinners. He deals sweetly with us, convicting us of our sin, but He doesn’t then infer that sin reigns in us, that we are children of darkness, or that we are under God’s wrath. Satan’s conniving is not sweet at all, but it is full of sting: you are a lost hypocrite, not a child of God, and sin reigns in you. The Spirit’s conviction is followed by sweetness: God forgives you in Christ.
Another way Goodwin put it is that Satan presents our sins to us alone, by themselves, with the intention of making us forget God’s mercies and comforts. Satan doesn’t remind us of our sins and our Savior. He makes our sins bigger and supremely visible while making God’s mercy small and invisible. The Holy Spirit works in the opposite way: he convicts us of sin, but with the purpose of driving us to the mercy of God in Christ. The Holy Spirit reminds us that sin does indeed abound in us, but then he tells us that grace abounds all the more. The Spirit convicts us of sin, but then sweetly brings us to the Savior.
Satan may attack us and make our lives miserable sometimes, but we can press on knowing 1) that Christ’s blood has washed all our sins away, and 2) that the God of peace will soon crush Satan under our feet (Rom 16:20). Then Satan will never be able to touch or torment us again, because he’ll be where he belongs: in the lake of eternal fire.
(The above references to Thomas Goodwin’s book is found in volume 3 of Goodwin’s Works.)