On God's will and the Supposed Decretive, and Preceptive will of God.

"Dr. Clark holds that man's knowledge of any proposition is identical with God's knowledge of the same proposition. Any proposition has the same meaning for God as for man. The complainants deny this. As an item of interest we may mention here that during the examination of Dr. Clark by the Presbytery of Philadelphia the question was asked him: 'You would say then, that all that is revealed in the Scripture is capable of being comprehended by the mind of man?" And the answer was given by him: 'Oh yes, that is what it is given us for, to understand it.'" - Gordon Clark, The Clark-Van Til controversy.

"The opponents may at this point claim that Calvinism introduces a self-contradiction into the will of God. Is not murder contrary to the will of God? How then can God will it?
Very easily. The term will is ambiguous. The Ten Commandments are God's perceptive will. They command men to do this and to refrain from that. They state what ought to be done; but they neither state nor cause what is done. God's decretive will, however, as contrasted with his precepts, causes every event. It would be conducive to clarity if the term WILL were not applied to the precepts. Call the requirements of morality commands, precepts, or laws; and reserve the term will for the divine decree. These are two different things, and what looks like an opposition between them is not a self-contradiction. The Jews ought not to have demanded Christ's crucifixion. It was contrary to the moral law. But God had decreed Christ's death from the foundation of the world. It may seem strange at first that God would decree an immoral act, but the Bible shows that he did. This point will be discussed more fully later on; but though it may now seem strange, it should be clear at least that a clear definition of terms by which two different things are not confused under one name removes the charge of self-contradiction.
When the term will is used loosely there is also a second distinction that must be made. One may speak of the secret will of God, and one may speak of the revealed will of God. Those who saw self-contradiction in the previous case would no doubt argue similarly on this point too. The Arminian would say that God's will cannot contradict itself, and that therefore his secret will cannot contradict his revealed will. Now, the Calvinist would say that same thing; but he has a clearer notion of what contradiction is, and what the Scriptures say. It was God's secret will that Abraham should not sacrifice his son Isaac; but it was his revealed will (for a time), his command, that he should do so. Superficially this seems like a contradiction. But it is not. The statement or command, 'Abraham, sacrifice Isaac,' does not contradict the statement, at that moment known only to God, 'I have decreed that Abraham shall not sacrifice his son.' If Arminians had a keener sense of logic, they would not be Arminians!" - Gordon H. Clark, The three R's