My view of sin would be the one described by the Urantia Book as is my view of evil and iniquity. The terms "evil", "sin" and "iniquity" are frequently thrown around as if they were equivalent, but there are definite distinctions between the use of the terms. I would sum them up as follows.
evil: Mistaken or bad judgment, even if the intention was for good. (Bad judgment according to whom? God, of course.)
sin: Deliberate choosing to do evil or go against the will of God.
iniquity: Wholehearted and persistent devotion to sin.
The following are some quotes from the Urantia Book regarding these three terms. There are many more which help further define the terms, but I chose some which I felt were most clear and succinct.
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3:5.15 The possibility of mistaken judgment (evil) becomes sin only when the human will consciously endorses and knowingly embraces a deliberate immoral judgment.
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130:1.5 Jesus' last visit with Gadiah had to do with a discussion of good and evil. This young Philistine was much troubled by a feeling of injustice because of the presence of evil in the world alongside the good. He said: "How can God, if he is infinitely good, permit us to suffer the sorrows of evil; after all, who creates evil?" It was still believed by many in those days that God creates both good and evil, but Jesus never taught such error. In answering this question, Jesus said: "My brother, God is love; therefore he must be good, and his goodness is so great and real that it cannot contain the small and unreal things of evil. God is so positively good that there is absolutely no place in him for negative evil. Evil is the immature choosing and the unthinking misstep of those who are resistant to goodness, rejectful of beauty, and disloyal to truth. Evil is only the misadaptation of immaturity or the disruptive and distorting influence of ignorance. Evil is the inevitable darkness which follows upon the heels of the unwise rejection of light. Evil is that which is dark and untrue, and which, when consciously embraced and willfully endorsed, becomes sin.
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75:4.3 Good is the carrying out of the divine plans; sin is a deliberate transgression of the divine will; evil is the misadaptation of plans and the maladjustment of techniques resulting in universe disharmony and planetary confusion.
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89:10.2 Sin must be redefined as deliberate disloyalty to Deity. There are degrees of disloyalty: the partial loyalty of indecision; the divided loyalty of confliction; the dying loyalty of indifference; and the death of loyalty exhibited in devotion to godless ideals.
89:10.3 The sense or feeling of guilt is the consciousness of the violation of the mores; it is not necessarily sin. There is no real sin in the absence of conscious disloyalty to Deity.
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148:4.6 "By nature, before the rebirth of the spirit, mortal man is subject to inherent evil tendencies, but such natural imperfections of behavior are neither sin nor iniquity. Mortal man is just beginning his long ascent to the perfection of the Father in Paradise. To be imperfect or partial in natural endowment is not sinful. Man is indeed subject to evil, but he is in no sense the child of the evil one unless he has knowingly and deliberately chosen the paths of sin and the life of iniquity. Evil is inherent in the natural order of this world, but sin is an attitude of conscious rebellion which was brought to this world by those who fell from spiritual light into gross darkness.
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67:1.4 There are many ways of looking at sin, but from the universe philosophic viewpoint sin is the attitude of a personality who is knowingly resisting cosmic reality. Error might be regarded as a misconception or distortion of reality. Evil is a partial realization of, or maladjustment to, universe realities. But sin is a purposeful resistance to divine reality -- a conscious choosing to oppose spiritual progress -- while iniquity consists in an open and persistent defiance of recognized reality and signifies such a degree of personality disintegration as to border on cosmic insanity.
67:1.5 Error suggests lack of intellectual keenness; evil, deficiency of wisdom; sin, abject spiritual poverty; but iniquity is indicative of vanishing personality control.
67:1.6 And when sin has so many times been chosen and so often been repeated, it may become habitual. Habitual sinners can easily become iniquitous, become wholehearted rebels against the universe and all of its divine realities.