If a man has the correct response to sin and believes in the Lord Jesus Christ, he can be justified before God. God will look upon him as he looks upon the Lord Jesus. Every sin that the believer commits has already been dealt with when Jesus bore the sins of the world.
But something else happens to the believer. The Holy Spirit comes and lives in every believer. Paul says to Timothy “guard the good deposit that was entrusted to you – guard it with the help of the Holy Spirit who lives in us.” (2 Timothy 1:14)
The work of the Holy Spirit
Jesus promised that the Holy Spirit would come into the world when he left and he said that “when he, the Spirit of truth comes, he will guide you into all truth.” (John 16:13).
So one work of the Holy Spirit is to guide believers to know truth, i.e. to believe the right things.
Another work is to help the believer to become more holy, in fact to become more like Christ. – Paul writes to the Corinthians that Christians “are being transformed into his likeness with ever-increasing glory.” (2 Corinthians 3:18).
Still far from perfect
Although a Christian is being “transformed,” it is an ongoing process. Certainly the believer will never be good enough to go to heaven on his own merit. As Paul points out to the Galatians: “I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing.” (Galatians 2:21).
However, there should be a visible change in the lives of Christians. If there isn’t, this may be a sign of false conversion. Christians should sin less and less as they mature.
Jesus was hated
It is important to note that Christians are being transformed into the likeness of the Lord Jesus. Now some people like to think of Jesus as a kind of hippy who was a pushover who let anybody do whatever they liked. This is not the case. Jesus often used very strong language to declare tough teachings – see Matthew 23 for an example.
One thing that Jesus declared was “I am the way and the truth and the life. No one comes to the Father except through me.” (John 14:6). In this statement alone he casts away all other religions. It was for his exclusive claim on truth and for other similarly unpopular claims that the religious leaders of the time put him to death.
In a similar way, don’t expect that non Christians will like everything that a Christian believes. In fact, part of a Christian’s sanctification will make him less popular with non Christians.
Jesus said: “If anyone would come after me, he must deny himself and take up his cross and follow me.” (Matthew 16:24).
Don’t forget that the Roman cross was a cruel and shameful way to die. You hung exposed to the world until you died. Jesus was telling his followers that they can expect great hardships.