The argument from free will is an argument against the existence of God which contends that omniscience and free will, properties ascribed to God by most monotheistic religions, are incompatible, and that any conception of God which incorporates both properties is therefore inherently contradictory. The argument goes as follows:

1. By the definition of "free will", if God has free will, then at any point in time he may either choose to do a certain thing or choose not to do it.
2. By the definition of "omniscience", an omniscient God knows everything that will happen in the future, including all of the choices he will make at any future point in time.
3. By the definitions of "knowledge" and "choice", if one knows what choice one will make in the future, one will not be able to make the opposite choice.
4. If God is omniscient, then he is incapable of choice.
5. God can not both be omniscient and have free will.

The usual response to the above argument states that God exists beyond the constraints of linear time, and that the temporal terminology used above is meaningless when applied to him.

A modified version of the argument from free will has been used by some theologians to argue that God's omniscience and Man's free will are incompatible. The basic logic is the same- if God knows what we are to choose before we choose it, how are we free to choose otherwise? This argument is essential to the doctrine of predestination.