Because through Christ Jesus the law of the Spirit who gives life has set you free from the law of sin and death. For what the law was powerless to do because it was weakened by the flesh, God did by sending his own Son in the likeness of sinful flesh to be a sin offering. And so he condemned sin in the flesh, in order that the righteous requirement of the law might be fully met in us, who do not live according to the flesh but according to the Spirit. Those who live according to the flesh have their minds set on what the flesh desires; but those who live in accordance with the Spirit have their minds set on what the Spirit desires. The mind governed by the flesh is death, but the mind governed by the Spirit is life and peace.
The Old Testament Law meant that although God’s people had made sacrifices to him, their sin would never be fully cleansed because humanity would always sin, due to our sinful nature (the flesh)
Therefore, God sent Jesus Christ as the perfect sin offering – an atonement for Christianity. However, people believe that when they give their live to Christ, although they are saved; some carry on doing things that would be classed as sinful in the Bible.
This is what’s incorrect
Although we are saved by the grace of God and atonement – it is not the full Gospel…
In John 14:26 it talks more about the Holy Spirit. He was sent to guide us into being more Christ like and therefore if we feel the spirit leading us or convicting us about our actions or thoughts, it is then that we should address these things and repent.
God has the complete solution to sin: We receive salvation from the penalty of sin through Jesus but the full and complete salvation comes from Jesus AND the power of not sinning can only come from the Holy Spirit.