One method of dividing up the actions that God is unable to perform results in 2 options: Actions that men (also) cannot do and actions men can do
Attributes of God are similarly categorised. Attributes of God that man can have to a degree are called communicable. Examples would be love or mercy. Attributes that God has and we do not are called non-communicable. An example would be omnipotence.
Actions that neither men nor God are able to perform belong to the category of logical impossibilities. These actions require breaking the law of non-contradiction. Asking God to both do and not do something in the same way at the same time is logically impossible. Asking God to both have an attribute and an attribute that contradicts it is logically impossible. God cannot make a rock too big to lift. God cannot be both unchangeable and changeable in the same manner.
There are also actions that humans are able to perform that God is not able to perform. This seems to solely relate to the realm of sin therefore they are actions that abuse a good; they create an evil. Evil is a distortion of an underlying good. Therefore God is unable to perform them because he would be doing evil. An example would be lying. Lying is a distortion of truth, truthfulness is an attribute of God. For God to lie would be a denial of his nature.
There is a subcategory of actions that men can do and God cannot that deserves mention. There are some actions that are limited to men because its definition excludes the possibility of applying to the divine. An example would be murder. This requires some explaining.
God and men can both kill humans. Killing is defined as removing a life. Now this can be allowed as in the case of war or capital punishment, disallowed as in the case of murder, or accidental (because we live in a fallen world) as in the case of manslaughter.
Murder is disallowed because it is the unwarranted removal of life. God created us and owns us. We must obey him and he has told us that we are not to murder, not to destroy the imago dei. This prohibition clearly is one that can only apply to men (and possibly angels). God cannot destroy life without his own permission. If God does destroy life it means he has permitted himself to. Therefore God is unable to murder because the definition of murder does not apply to deity. One could argue that it was at least theoretically possible for Jesus to murder during the incarnation if he took a life without the implied or express permission of the Father, though that takes us into another debate, perhaps for another time.
The limits of God
- God cannot perform logical impossibilities.
- God cannot sin.
- God cannot do things defined in terms of men.
- Man cannot perform logical impossibilities.
- Men can sin.
Further, even if God cannot sin as deity, it is possible that Jesus could as man even though he choose not to.