Theological fatalism proposes that an omniscient God and free will are incompatible, where free-will is simply defined as the ability to choose between alternatives.

For example:

1. God is omniscient.
2. Since God is omniscient, God has infallible foreknowledge. [1]
3. If God has infallible foreknowledge that tomorrow you will engage in event X, then you must invariably engage in event X.
4. You must invariably engage in event X. Modus Pones [3] [2]

Therefore, free-will is not possible since you have no alternative except to engage in event X. In the event that you do not fulfil event X, then God is not omniscient. Alternatively, if you engage in event X, then you don't have free-will on account of the inability to choose another alternative.

An opposing argument can state:

1. God is omniscient
2. Since God is omniscience, he is also infallible.
3. If God has infallible foreknowledge that tomorrow you will engage in event X, then you will freely choose this based on your free will, not obligation or lack of choice in event X.
4. You still have free will to engage in event X, it's just God knows your choice before you make it, you are not obliged to make choice 'X', anymore than choice 'A'. If you were going to change your mind, God would have seen that also, so you still have full free will in all matters. Also, you will still make the same choices [with free will] even if God chose to not see the future. Seeing the future or not does not alter your free will.

• An interesting point many people omit when proposing arguments against God's omniscience and free will is the active involvement, or not, of God in the matter. If God chose to reveal His foreknowledge of events, then this would not only alter reality by cause and affect, but would also remove the free will to do any alternative, as God would be obliged to force His predictions to prove His foreknowledge correct. Many incorrectly assume in their argument of omniscience that God has somehow done this, even when there is no evidence for such, like proposing that God has revealed the details of individual's life, would immediately refute free will. Often this blind assumption is inserted as a straw man to take the argument in another direction away from pure passive foreknowledge.

• With passive foreknowledge, if it were kept hidden, it would not invalidate free will in any logical or rational way. The individual choosing event X, would be making the exact same choices regardless of whether God knew the choices beforehand or not. God Knowing or not knowing the future [passively] would not alter the free will of individuals at all. The demise of free will would only logically come if God made His knowledge public in regard to the free will choice of individuals; this would therefore alter future free will, and make it an obligation. One simple illustration could be a psychic person foreseeing someone the other side of the world tripping and breaking their leg when they run to catch a bus. The psychic would not be altering reality be foreseeing this event, as this event would still happen regardless of whether someone has seen it or not, the same application can be applied to God's omniscience, as long as it is passive, and non-interfering with reality or other's knowledge of it, then it is not contravening the free will of humans.

See also

• Newcomb's paradox