The truth is that every man is all the time a servant (slave) to one or another master. The Christian experiences two kinds of servant-hood in their lives; 1) the flesh, or 2) Christ as righteousness.

Romans 6:19 (KJV) I speak after the manner of men because of the infirmity of your (sinful) flesh: for as ye have yielded your members servants (Gk. doulos, slaves) to uncleanness and to iniquity unto iniquity; even so now yield your members servants to righteousness unto holiness.

All men are the servants of Sin before regeneration, but after regeneration, we have a the freedom to make choices day by day and moment by moment, as to our walk. The question is "Will we choose to yield to the sinful impulses emanating from our flesh (cf., Rom 7:17-24) and be Sin's servant, or will we yield to "the Spirit of life in Christ Jesus" who indwells our spirit? Christians need to know that Christ's righteous "Spirit of life" and nature is spontaneously working within their spirit, having the power to overrule the operation of "Sin in the flesh," We need to will trust and yield to Christ in us. Being regenerated, we live under a new paradigm; we have the operation of Christ's "Spirit of life" within us.

Romans 8:2, 13 For the law (normal operation) of the Spirit of life in Christ Jesus hath made me free from the law (normal operation) of sin and death. ... 13For if ye live after the flesh, ye shall die: but if ye through the Spirit (of Christ) do mortify (deaden) the deeds (acts) of the body, ye shall live (zao, experience His life.

This remedy appears when man a man hears the gospel and is confronted with a life choice... to receive God's free salvation that is in Christ, or not. God sent His "Only Begotten Son" into the world so that twisted man might be made straight by their union with Christ in His death and His life. This comes not through man's self-effort, but only through simply receiving God's reconciliation that is in Christ Jesus, and simultaneously receiving the resurrection life of the Son of God, who bears the Father's life and nature, with Jesus' resurrected humanity. Christ's "Spirit of  life" has the power to free men and renew a man's soul, making man an expression of Christ's life and nature. This then would be... man as God intended.

The new nature for man "in Christ" is that of "the Light." Our nature is always with us even if we at times do something at odds with our nature. All believers have already become light by having received Christ who is "the light."  Thus Paul wrote "... NOW Are Ye Light in the Lord" (Ephes. 5:8).

As stated earlier, God is a "consuming fire." He burns with desire... desire to give and outflow to others. Light is fire in its life-giving form. The light we enjoy comes from the ever-burning Sun and sustains our physical lives. This is also seen by His eternal begetting of His Son in His likeness. God's "fire-self" was expressed and eternally transmitted as being God's "Light-self"... in the person of His Only Begotten Son. God's burning desire to flow out to others as love., light, and life was expressed in His then "giving his only begotten Son" for the sins and Sin of the world. If men will simply receive Him, His salvation, His death and His life to be their death and new life.

I've heard it said, "Where fire burns, light blesses." Jesus is the light expressing God's fire, being called "the light of life." John 8:12 Then spake Jesus again unto them, saying, I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life.

The light of Christ then is nothing less than that of the eternal God, the lover of others, the God who burns with desire to give, love, and be merciful with His graces. John wrote "…God is light..." (1Jn 1:5)

And we as believers, by the deposit of Christ's indwelling life and nature, are now "light" to a dark and dying world; particularly as we learn to yield to His inward promptings and restraining.