New Testament Commands
Why obey the New Testament Commands?
Although Paul clearly taught that salvation is by faith and not by works (Eph. 2:8,9), we never know for sure if our faith is a saving faith, that is, if we have placed our faith in the real Jesus. Sadly, many people have placed their faith in an imaginary or politically correct Jesus, not the Jesus of the Bible. Jesus Himself said that many people will be shocked on Judgment Day to realize that Jesus never knew them (Mt. 7:21-23; Lk. 13:23-28). The apostle John wrote that some people who think they know Jesus actually never knew Him (1 Jn. 2:4). In both cases, the key element for testing ourselves is obedience.
This means that obedience to the NT commands is the ultimate way of gaining assurance of salvation (not for gaining salvation, as some have mistakenly taught). The distinction may seem slight, but it is large, because faith is commitment without knowing:
(Note that the NIV version wrongly translates it, "Faith is being sure of what is hoped for and certain of what we do not see." This is misleading, because we cannot be certain of the future and of the unseen.)
So, the best we can have is assurance of salvation. (For further study, see Rom. 8:24,25; 11:22, 1 Cor. 15:1,2; Col. 1:23; Heb. 3:6,14). This means that we must work out our salvation with fear and trembling (Ph. 2:12), test ourselves regularly to see if we are really in the faith (2 Cor. 13:5) and make our calling and election sure (2 Pt. 1:10). It's only on the day of Judgment that we'll be able to know if our names are written in the Book of Life (Rev. 20:11-15).
Jesus never gave commands that cannot be kept. Just because many "Christians" ignore some commands today, does not mean you can! To see an exhaustive list of the commands Christians need to follow, you can read the book, All I Have Commanded.
we under grace and not law?
However, in New Testament times believers in Jesus Christ are obligated to obey the law of Christ (see 1 Cor. 9:21). His law actually has higher standards than the Mosaic Law, because it deals with attitudes and motives. As the Apostle Paul wrote:
He's talking about the law of Christ.