Believers have been transformed by the saving faith in Jesus Christ and indwelled by the Holy Spirit. This gives us the new nature of righteousness, however, we still possess the old nature which can rule over our flesh. So it is necessary that we battle against the flesh by relying on the Holy Spirit of God in connection with Scripture, prayer, and obedience to Christ.
Because the flesh lusts against the Spirit (and the Spirit lusts against the flesh) we are in spiritual warfare every moment of our lives. When we fail to stay focused on Christ we can be distracted and/or deceived by the flesh. The longer we remain distracted we more insensitive we become toward sin and begin a downward spiral spiritually. So we must regularly examine ourselves to make sure our walk with Christ is genuine and sincere. John (in 1 John 1:9 – 2:29) gives us characteristic of believers which reveals our spiritual sincerity:
1 – If we have fellowship with him by walking in the light (righteousness of God )rather than walking in the darkness (sinful ways of the flesh and the world).
2 – If we confess our sin.
3 – If we keep his commandments (Check the Sermon of the Mount – Mat 5-7 and John 14 – 16.
4 – If we walk as he (Jesus) walked.
5 – If we love the brethren (the other believers)
6 – If we love the things of God rather than the things of the world. See Titus:1:16
7 – If we continue in truth of God’s Word rather than abandon it for the false message(s) of the world.
8 – If we profess Christ before men rather than deny him before men
9 – If we abide in him and his Word
10 – If we live righteously because we know he is righteousness.
Insensitivity toward sin is a sign of carnality (backsliding) or possibly being unregenerate (unsaved).
If we can walk in the counsel of the ungodly, stand in the way of sinners, or sit in the seat of the scornful – we are becoming insensitive to sin and eventually will end up in the company of the unrighteousness. (Psalm 1)
Sensitivity toward the things of God reveals the spiritual foundation of our hearts. If we love the Word of God (the saved do), meditate on it day and night (the saved do), and keep his commandments (the saved do) then we will confess sin, repent from sin, and fight to resist the temptation to sin.
Anyone that tells you different is a deceiver.