Calvinists are theistic determinists. The Westminster Confession of Faith, declares that
"God, from all eternity, did, by the most wise and holy counsel of His own will, freely, and unchangeably ordain whatsoever comes to pass” (Westminster Confession of Faith, III/i).
Did you hear that? They are saying that God unchangeable ordained whatever comes to pass! This means:
Every child molestation was ordained by God.
Every war was ordained by God.
All war crimes were ordained by God.
The unbelief of man was ordained by God.
Every apostasy in the visible church was ordained by God.
We could go on … are you inspired to worship this God yet?
If this is so, then two questions arise:
1. How is man really guilty of his sins, if God decreed beforehand all his sins and made them happen. By this understanding, God made all these sins happen, and there was no way any of them could have been avoided? How can man be guilty for things he could not have prevented?
2. How does God Himself escape culpability for all the evil which He ordained?
"Hard determinists" tell us that even though it seems logically impossible to ascribe guilt to mankind or blamelessness to God under this scenario, we should do so as "an act of faith" and leave our reason at the door.
Most Calvinists however, are NOT "hard determinists". Whether they know the term or not, most calvinists are "compatibilists". What this means, is that they believe that God's prior determination of all things is still compatible with man's responsibility and guilt. The way this is normally done is by saying asserting that
1. Man always acts according to his desires.
2. A man acting according his desires is in some sense free.
3. Because he is free in this sense, he is morally responsible for his sins.
In other words, mankind is guilty because he really wanted to do the wrong thing – he desired sin, so therefore he is guilty.
I dispute the idea that man always acts according to his desires. If this were so, how could it even be POSSIBLE for a man to "deny himself"? But leaving that issue aside, if we grant that a man always acts according to his desires, then I don't see how it leaves man morally responsible, because there is still NO WAY he could have done anything other than what he did, when he sinned! (in the deterministic viewpoint, that is).
The problem with all this is that in theistic determinism, it is GOD who ordains the things men desire, and it is also GOD who creates the circumstances which give occasion to the desires to lead to sin.
So by making men to desire evil things, and then putting or "ordaining" temptations such as men would desire to be in their path, God is actually the ARCHITECT of all this sin anyway.
In this viewpoint, people only desire to sin because God made them desire it, and then arranged the opportunity to sin, which would be irresistable to the sinned. HORRIBLE!
On the contrary the Scripture says:
Let no one say when he is tempted, "I am tempted by God"; for God cannot be tempted by evil, nor does He Himself tempt anyone. But each one is tempted when he is drawn away by his own desires and enticed.
Temptation and not the commitment to sin is ascribed to the presence of evil desires, as well as to the activity of enticement, which is done by satan's minions.
The mere presence of desires does not guarantee that a man will sin.
But even if it DID, if God is the one arranging and decreeing and determining all these necessary and sufficient conditions for sin to happen, then GOD is the one behind the sin.
I don't see them how theological compatibilism solves ANY problems for determinists. You may as well just say, "It doesn't make any sense to the mind of man, but "by faith", we trust that WE, and not GOD, are guilty of being the authors and architects of all that is sinful and evil.
A belief in a limited free will of man avoids all these problems.
I am not saying that the will of man is TOTALLY free. Indeed, sinners are "slaves to sin" and to some extent their conditioning and past sins makes it impossible for them to resist certain sins. But not ALL THE TIME. People have a history of sinful acts that they have freely chosen, in the sense that they could have, had they so chosen, to avoid at least some of them. In Christ, we have the opportunity to break the conditioning and have the genuine opportunity to not sin in ways we formerly would have been driven to. Also, sinners have the opportunity to say "No" to sin because of the "prevenient" grace God gives them even if they are not regenerate people.
For more information, I refer you to this article by Robert Hamilton.