Being in the presence of evil does not equate to being a part of it. God and satan were close enough to have a conversation in the Bible. That doesn't challenge His omnipresence. satan was still in Heaven the moment before he was cast out. God was present, but not a part of it.
Calvinists fully believe that we can reject God. In fact, we're born to do it. :)
I think, the distinctions we are talking about here are very subtle. Do we all agree that God did not create evil, and that evil requires an act of will? I still think that the metaphore of light is the best. To make darkness one has to erect a barrier. Darkness then is very tangible behind the barrier. Yet it is not created by God. Light is created by God and the barrier is. The positioning of the barrier so that it produces darkness is an act of sinful will.
God is present everywhere but not everywhere in the same sense. For example, we beleive that He is present during luturgy in a special way, and during a football game in a different way.
Which was the point of my reply to your statement that evil is absence of God. Evil can only be the result of the free will to reject God. If there is no free will, there is no possibility of evil, FK.
Thus, scripturally, there is no need to specifically qualify our will as free any more than there is a need for the Bible to specifically use the term Holy Trinity for both to be true and obvious to all (except to Calvinists).
Calvinists fully believe that we can reject God.
No, Calvinists fully believe that we must reject God. You confirmed that in the very next sentence In fact, we're born to do it. If we are born to reject God, we do not reject God willingly. That much we agree. But once made aware of God, you continue to believe that, by virtue of our nature, we must reject Him unless He compels us otherwise. At no point do Calvinists admit that man, by virtue of his intellect, chooses God or chooses to continue to reject God.
Now, we are born without the knowledge of God but, when God knocks (repeatedly) on our hearts, by virtue of our nature we tend to reject God, but by virtue of our intellect, we are free to either reject or accept His love, a decision we make freely because He endowed us with that freedom.
I look at it as I would look at an addiction. We follow "feels-good" principle of our flesh, by nature, even if our intellect tells us that it may not be good for us. We will repeatedly be drawn to do what is necessary to continue the addiction against our better judgment, so we need help. But help can come only when you, in your mind, freely decide, by virtue of your intellect, that the addiction (no matter how good it feels) is wrong, and wish to overcome it. You then seek help because it is impossible to overcome on one's own. It is only then that we realize that help was always there.
This all goes back to my original objection to Calvinism, namely that denying free will by necessity denies the possibility of evil (and makes evil, sin, and the need for our redemption meaningless). By necessity, our actions, then, are simply an extension of God's will. Since God cannot choose evil, the fact that evil exists, proves that theory false.