"Keith"
With all due respect your understanding of this verse is not quite correct.
2Cor. 4:4 reads "...in whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them."
This verse clearly states that it is the god of this world (a reference to the Evil One - Satan) who has blinded the minds of those who do not believe the truth in order to prevent them from responding to the gospel. The light to which this verse refers is the light of the gospel of Christ and not, as you assert, the image in which mankind is made. It is Christ Himself (not the gospel) who is, in His own unique way, the perfect image of the invisible God (Heb.1:3(a)).
However, you are correct in your belief that human beings are made in the image of God (Gen.1:26-27) and that originally our first parents (Adam and Eve) were indeed made in the image of God whilst in perfect communion with God (and therefore in the light (1Jn.1:5-7)).
Now, however, as a result of their rebellion and the subsequent fall, the image in which humans are made is marred because of sin and all humanity is now born into rebellious darkness. The image has not been destroyed completely, only marred. Those who are true believers, who are walking in the Spirit, are actually walking with God in the light having crossed over from darkness to light, from death to life (Jn.5:24). At the resurrection that image will be restored back to it's original perfect state as we shall once again be in perfect communion with God (hasten the day!) Those who are not true believers, whilst still bearing the image of God, are actually still walking in the darkness of rebellion and death. If they do not repent and become true believers during the time of God's grace then, on the day of God's judgement they will be cast into the everlasting Lake of Fire, prepared before the foundation of the world, for the devil and all his angels, there to remain forever in the purpetual rebellious darkness of death (Isa.66:24).
Hope you find this explanation helpful?
Simonline.