After a person sins they are to offer a sacrifice to obtain forgiveness. The sacrifice to obtain forgiveness in the Old Testament Law was a bull or goat etc. In the New Testament the sacrifice for all sin is Jesus Christ.
In other words if a Christian asks for forgiveness Jesus is faithful and just and forgives them 1 John 1:9.
They are then free from sin and are in right relationship, with God -- they are righteous. This is the righteousness of the Law. The righteousness contained in the Law is conferred upon them as a result of having complied with the law.
. 1Jo 1:9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness. (KJV)
If a Christian confesses their sin to God they are forgiven and are made righteous. Their confession to God (through Christ) is the same thing as offering a sacrifice in the Old testament, only under the new testament or covenant we simply confess to be forgiven because Jesus is the sacrifice for all sin.
The “cleansing” of 1 John 1:9 is what Paul desired as He wrote in Philippians chapter 3. The righteousness that comes by faith is the righteousness (being right in God’s eyes) that involves not sinning in the first place.
The "cleansing" or transformation needed is from the man of sin or from this present body of death. It is not accomplished by dying and receiving a new body but by overcoming the tendency to sin, which is present in this in this flesh body. Romans 6:6 shows this when it speaks of the destruction of the body of sin and then after that the continuing life which is characterized by not serving sin. Of course Jesus accomplishes this transformation for us as He teaches us to stop sinning. The wording Paul uses to describe this transformation or cleansing is “the destruction of the body of sin” and the subsequent life thereafter being free from sin.
Ro 6:6 Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin
The “cleansing” spoken of in John 1:9 is what Paul is speaking of in the following verse. Not the forgiveness after a person sins but the transformation into a person who does not sin.
Ro 7:24 O wretched man that I am! who shall deliver me from the body of this death? {the body...: or, this body of death }
Paul said that His righteousness came from the law, but he longed for and pressed towards the righteousness that is from God by faith.
Php 3:9 And be found in him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith:KJV
To follow Jesus example: Paul wanted to attain to the resurrection from the dead through this righteousness by faith.
Ro 6:10 For in that he died, he died unto sin once: but in that he liveth, he liveth unto God.
Jesus died to sin (He was dead to sin) and rose to the resurrected life in God before he died physically on the cross.
This is the resurrection spoken of in Colossians 3:1. The resurrection from being in the sinful state to the state of being dead to sin and alive to Christ.
Ro 6:11 Likewise reckon ye also yourselves to be dead indeed unto sin, but alive unto God through Jesus Christ our Lord. (KJV)
