God's Word speaks about Christ's work on the Cross being a Complete work of saving or salvation (Hebrews 7:27; Hebrews 9:12; Hebrews 10:10). How, then, can a "hidden sin" be a problem? There is no "hidden sin" in a Complete Work of Salvation.
The key to walking or living in freedom for Christians is not to get addicted to looking for every mistake around the corner. Christians still continue to sin after declaring to follow Jesus, but their nature should be changed to not be inclined toward sin anymore. As a help, the Holy Spirit through James instructs us - "Therefore confess your sins to each other and pray for each other so that you may be healed." (James 5:16) However, Christians should not be worried, concerned or focused on sin. This gives me the impression of walking on spiritual eggshells all the time. Instead, we should be Salvation minded.
Paul in his letter to the church in Ephesus helps us to be Salvation minded when he encourages them and us to put on the Helmet of Salvation daily (Ephesians 6:17). A great deal of freedom for the Christian can be realized when he/she fully grasps - "Therefore, there is now no condemnation for those who are in Christ Jesus," - Romans 8:1 Whenever Christians stumble in their walk or when they are on the straight and narrow, Father God is always looking at them through the Completed Work of Jesus Christ. Jesus said, "I am come that they might have life, and that they might have it more abundantly." - John 10:10 "Abundant life" does not include looking over your shoulder or holding your breath until you find some "hidden sin".
There is no way Father God can look to the left or to the right of Jesus when viewing us. There is no looking under or over Jesus when He sees the true believer. Father God looks at Jesus and His sacrifice as He beholds us. God the Father looks through Jesus' sacrifice as He gazes upon the Believer and because of Christ's Complete Work He continues to shower His kids with Love, Grace, Mercy, and Favor! It's all because of the Complete Work of Jesus Christ, my Lord and Savior! Hallelujah!
Hidden sins? There is no such thing. A complete.....Waste Of Time! Jesus paid it all! Live in His Completed Work!