We are not under the letter of the law Romans 6:14 we are under the Law of Christ which is the call to love others as He loved us and to believe in the one God has sent which is Christ.
For some people the Law of Christ does not exist, yet it is biblical. Jesus never once said if you love Him keep the 10 commandments (i.e., in the form of the letter). He said if you love me keep MY commandments. What are His commands? The answer is found in John 13:34-35 Notice that Christ states a new commandment that on the surface seems to be the same as Leviticus 19:18 which is "Love your neighbor as yourself" BUT actually it's a bit deeper because Jesus states "Love others as I HAVE LOVED YOU" thus a sacrificial love that requires death to the flesh. This is the LAW OF CHRIST now written in our hearts if we are born again in the Spirit of God. Amazingly, many who advocate observance to the 10 commandments point to John 14:15 and John 15 where Jesus states "if you love me keep MY commands" they twist these verses stating that here is clear proof that Jesus was referring to the letter of the law (that is to say the 10 commandments) when in context with John 13:34-35 he was speaking of the Law of Christ the Law of the Spirit. Many also falsely cite 1 John 5 where the same John who wrote the Gospel of John states the commandments are not burdensome or grievous and in context with 1 John 3:23 and his prior writings in the Gospel of John he is referring to the Law of Christ. 1 John 3:22-23 says
And whatsoever we ask, we receive of him, because we keep his commandments, and do those things that are pleasing in his sight.
And this is his commandment, That we should believe on the name of his Son Jesus Christ, and love one another, as he gave us commandment. John 6:29 and John 13:34 No one can please God after the flesh and if no one can please God after the flesh when Jesus states if you love me keep my commandments He is referring to the Law of Christ which is the call to love other as He loves and no one can do that through the letter because the letter dominates the flesh. Peter clearly states how obeying this truth we are purified. "Seeing ye have purified your souls in obeying the truth through the Spirit unto unfeigned love of the brethren, see that ye love one another with a pure heart fervently: Being born again, not of corruptible seed, but of incorruptible, by the word of God, which liveth and abideth for ever." (1 Peter 1:22-23) And walk in love, as Christ also hath loved us, and hath given himself for us an offering and a sacrifice to God for a sweetsmelling savour. (Ephesians 5:2)
Now that we do not serve after the letter but in the spirit we see that the Law of God is fulfilled by the following two verses in John (John 6:28-29 and John 13:34-35) which reflects the 2 greatest commandment:
(JOHN 6:28-29) "Then said they unto him, What shall we do, that we might work the works of God? Jesus answered and said unto them, This is the work of God, that ye believe on him whom he hath sent." (John 13:34-35) "A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another." (1 John 3:22-23) "And whatsoever we ask, we receive of him, because we keep his commandments, and do those things that are pleasing in his sight. And this is his commandment, That we should believe on the name of his Son Jesus Christ, and love one another, as he gave us commandment." (Notice how this reflects John 6:29 and John 13:34) If we truly are born of God and love the Lord with all our hearts, souls and minds we will NOT or should NOT give him dead works produced by our flesh that is subject to the letter since we cannot obey it to the "T" and it is not of faith. However, God commands us to believe in His Son and abide in His love because Jesus abode in His Father's love perfectly obeying unto death. That covers the first great commandment. The second great commandment is to love thy neighbour as thyself and that is fulfilled in the Law of Christ where Jesus states Love others AS I HAVE LOVED YOU which was to the death! This requires that we crucify our flesh daily to love after He loves which is spirit! (Matthew 22:36-40) "Master, which is the great commandment in the law? Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the law and the prophets." Observe these verses from (Hebrews 5:8-10) signifying how we are to Obey Christ which abode in His Father's love perfectly! "Though he were a Son, yet learned he obedience by the things which he suffered; And being made perfect, he became the author of eternal salvation unto all them that obey HIM; Called of God an high priest after the order of Melchisedec." NOW Whosoever denieth the Son, the same hath not the Father: he that acknowledgeth the Son hath the Father also. 1 John 2:23