Personally I too believe Calvinism and Arminianism are two example of extremes which lost the founding doctrine of Christ. Too much pondering on what is 'inside' the mind of God can lead to a distortion of the Gospel. There were many important and, notwithstanding the extremization of their view on the doctrine, imbued by Christ's life preachers and missionaries based on Calvinist and Arminian faith. But the Bible stands in the middle, at the center and not on the extremes.
In particular Calvinism. We are an image of God, and as God has a free-will, God's will, we have an image of it. We render honor and deference to God when our free-will matches to His one. But how we could do that if we have not a free-will? If we are a not complete image of God? Think, you have a free-will to do things for yourself. You can exercise your free-will rebelling to God (Adam's and Eve's first sin), or you rebel against the will of the prince of this world, Satan. Therefore it is the sin in the world [that evil allowed by God in His inscrutable design] that allows our free-will to match to God's one, or, in other words, to repair the damage provoked by the same free-will rebellion in the Eden's age. Remaining at the same time a free-will image of God.