What is meant by “you being evil”?
Answer: Perhaps we can respond to this from passages in Genesis 3, Mark 7:21-23, and 1 John 2:16?
First, suppose we reflect on Adam and Eve who were once innocent and fell from that state of perfection.
I. The first couple existed in a paradise where had they obeyed God (implausible, given the circumstances), they could presumably have lived forever. There was no decay, no disease, no death, and no animal predators to worry about. Their only challenge was the Tree of the Knowledge of Good and Evil.
II. After the first couple fell into temptation and ate of the Tree, something profound occurred. From the beginning, they apparently had no awareness of their nakedness, certainly not as anything sinful. Maybe we are to understand the reason they had no concern for such things is that they shared a common spiritual identity, an mutual consciousness in which they were at one with God, with each other, and with their surroundings, innocent as young children.
III. This suggests that before their transgression Adam and Eve possessed a superior supernatural awareness; they had no real sense of self, per se, but were united both intellectually and spiritually. Once they disobeyed God and had eaten of the Tree, it seems that this undifferentiated perfection was shattered; they became disassociated with one another into disunited self-identities.
IV. Our original parents were no longer at peace with God or with their environment. They became separate and distinct, spiritually and psychologically detached. Their disobedience deprived them of their blessed selflessness, replacing it with selfish personal identities. And, with an intense recognition of self, there is an awareness of what one does, what one can do to others, and what others can do to us.
There is a profound vulnerability associated with individuality. It is the immediate recognition that a person is entirely alone in their thoughts about themselves and their surroundings. The “self,” or ego, presents great restrictions because an intense responsibility arises with individual awareness: we are capable either of acting in accordance with God’s wishes or of behaving contrary to His commands and, thus, committing malevolent, evil acts.
Through this identity, we entertain all manner of enmities as described in Mark's Gospel:
Mark 7:21-23: “For from within, out of the heart of men, proceed the evil thoughts, fornications, thefts, murders, adulteries, deeds of coveting and wickedness, as well as deceit, sensuality, envy, slander, pride and foolishness. All these evil things proceed from within and defile the man” (cf. Jer. 17:9, emphasis added).
From these passages, it seems clear: everything that defiles us as human beings, that which makes us "evil," originates from our sense of self – our Pride. It is from this sickness that all other malignancies arise; we are then souls spiritually adrift from others. Author C.S. Lewis wrote about this dilemma:
The natural life in each of us is something self-centered, something that wants to be petted and admired, to take advantage of other lives, to exploit the whole universe. And especially it wants to be left to itself: to keep well away from anything better or stronger or higher than it, anything that might make it feel small. It is afraid of the light and air of the spiritual world, just as people who have been brought up to be dirty are afraid of a bath. And in a sense, it is quite right. It knows that if the spiritual life gets hold of it, all its self-centeredness and self-will are going to be killed and it is ready to fight tooth and nail to avoid that. (Mere Christianity)
Indeed, the self is the very foundation upon which we become our own god, blinded by our own narcissistic ambitions. Everything else becomes incidental as a means of gratifying the insatiable self. This must inevitably lead to our "being evil" as noted in the OP (Luke 11:13).
When we reflect on our very early years under the age of four or five, we had not yet formed any defining sense of personhood. We were largely unaware of the world and of all that it represents; we were oblivious to the dangers around us and might easily step directly in front of oncoming traffic. We lived a quasi-heavenly existence, at relative peace with ourselves and everything else: We had not yet eaten of the Tree.
As we contemplate the circumstances in the Garden, there seems to be a distinct parallel between the effects of consuming the forbidden fruit (disobedience to God) and our own awareness, beginning around those early ages (4 or 5). Prior to that, we have little conscious awareness of our vulnerabilities. Just as Adam and Eve, we do not recognize the evil that lurks around us. Note what Christ has to say, and think about why He said it:
Matthew 18:1-4: At that time the disciples came to Jesus and said, “Who then is greatest in the kingdom of heaven?” And He called a child to Himself and set him before them, and said, 'Truly I say to you, unless you are converted and become like children, you will not enter the kingdom of heaven. Whoever then humbles himself as this child, he is the greatest in the kingdom of heaven.'"
Christ has just proclaimed that humility, the absence of pride, is what exalts us. If that is true, then the opposite must also be true: Pride is that which demeans and diminishes us: it is why we are "evil".
By five years or so, we too begin to understand the difference between right and wrong. We recognize when we have disobeyed our parents and are conscious of our guilt –- just as if we too had partaken of the same deadly fruit. As we age further, we are intensely aware of ourselves as uniquely separate individuals and have become thoroughly unrighteous, evil beings.
This must surely explain why it is only when reach that age that we suddenly feel a desperate need to clothe ourselves. We are consumed by worries about what others might think. This same is true as fear often manifests itself when we step in front of a large audience. Many of us are consumed by what others might think of us, what they might do to us.
Unique, personal identity is not a blessing: it is a curse. It is being consumed by an intimate recognition of the evils with which one is capable, in stark contrast to the harmony one experiences before this individuation occurs.
This may explain what happened to Adam and Eve. Although they formerly possessed a conscious awareness, they did not possess an acute, self-conscious distinctiveness, one overwhelmed by feelings of detachment and isolation. This condition instantly reveals our nakedness, our evil –- all the ills that plague humanity.
1 John 2:16: “For all that is in the world [represented by the Tree], the lust of the flesh [desires for that which is forbidden] and the lust of the eyes [lust for self-satisfaction] and the boastful pride of life [to make oneself as God], is not from the Father, but is from the world.”