Paul realized that no man could obey the law fully; therefore, God’s immutable moral law would bring death to every man who thought they could find life by attempting to obey it. God’s law is permanent, just, holy, good, and could only be fulfilled by the God/Man Christ who is the only hope for depraved man.
“There is therefore now no condemnation to those who are in Christ Jesus, who do not walk according to the flesh, but according to the Spirit. …For what the law could not do in that it was weak through the flesh, God did by sending His own Son in the likeness of sinful flesh…that the righteous requirement of the law might be fulfilled in us who do not walk according to the flesh but according to the Spirit.” Romans 8:1-4
Paul summarized his argument by confirming that man is still in the flesh which is by nature sinful. Man’s only solution to that dilemma is to place his trust in the vicarious death of the sinless Christ and receive the Spirit of God within him to rule his life.
With God, there is no ‘plan B.’ His standard of righteousness had to be fulfilled by one in the form of man. Christ did that which no other man could do.
In his letter to the church in Galatia, Paul reiterated the requirement for God’s law to be fulfilled in total.
“For as many as are of the works of the law are under the curse; for it is written ‘Cursed is everyone who does not continue in all things which are written in the book of the law, to do them.’… Christ has redeemed us from the curse of the law, having become a curse for us…” Galatians 3:10, 13a
The central point in the above passage is that anyone who chooses to seek salvation by obeying the law must abide by the entire law which is impossible. Therefore, such a person is cursed. Christ has redeemed His chosen by paying their sin debt for them. He became the curse in their place. The only requirement for the redeemed is to have faith in the work of Christ. Such faith is also a gift of God.
Subsequent to the beginning of the church, the apostles revealed other detailed items included in God’s standard of righteousness. For example:
“Now the works of the flesh are evident, which are: adultery, fornication, uncleanness, lewdness, idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies, envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand…that those who practice such things will not inherit the kingdom of God.” Galatians 5:19-21
The practices Paul lists above are innate to the natural man. Such issues are included in God’s immutable righteousness and those who practice any of them will ‘not inherit the kingdom of God.’
The above practices are summarized in redeemed man’s responsibility towards his fellow man.
“For all the law is fulfilled in one word, even in this; ‘You shall love your neighbor as yourself.’” Galatians 5:14
If a man truly loves his neighbor and desires the best of God in his neighbor’s life, then he will instinctively fulfill the golden rule of conduct. That will fulfill God’s ‘law’ of righteousness required of him relative to his fellow man. Again, such is only possible if the Spirit of God dwells within him; and the Spirit is given to those who have placed their faith in Christ.
This great truth was illustrated in Paul’s letter to the Christians in Rome.
“Owe no one anything except to love one another, for he who loves another has fulfilled the law. For the commandments, ‘You shall not commit adultery.’ ‘You shall not murder,’ ‘You shall not steal,’ ‘You shall not bear false witness,’ ‘You shall not covet’ and if there is any other commandment, are all summed up in this saying, namely, ‘You shall love your neighbor as yourself.’ Love does no harm to a neighbor; therefore love is the fulfillment of the law.” Romans 13:8-10
Again, true love (agape love) towards one’s fellow man fulfills God’s required righteousness.