For we know that the law is spiritual:
but I am carnal, sold under sin.
Romans 7:14
The Christian life is a dichotomy, a constant warfare between the flesh and the spirit.
Romans 8:6-7 For to be carnally minded is death; but to be spiritually minded is life and peace. 7Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be.
Romans 7:18 For I know that in me (that is, in my flesh,) dwelleth no good thing: for to will is present with me; but how to perform that which is good I find not.
Galatians 5:16 This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh.
Man is a trinity: body, soul and spirit. our body, the flesh, has a mind of its own and is corrupt and subject to lust unto sin.
James 1:14-15 But every man is tempted, when he is drawn away of his own lust, and enticed. 15Then when lust hath conceived, it bringeth forth sin: and sin, when it is finished, bringeth forth death.
The flesh is self-centered, self-promoting, self-preserving, and self-gratifying; in a word, selfish. The law is spiritual and requires selflessness, taking all into consideration besides yourself.
Colossians 3:13-14 Forbearing one another, and forgiving one another, if any man have a quarrel against any: even as Christ forgave you, so also do ye. 14And above all these things put on charity, which is the bond of perfectness.
Upon salvation, we are sealed with the Holy Spirit of God and if we walk in the Spirit we will be strengthen to mortify the flesh and live the law of God.
Ephesians 1:13 In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,