Can God make a rock so heavy that even HE can't lift it?

It's a clever question, and it has had a standard answer for about eight hundred years. The trick is that the sentence describes nothing, and asking whether God can do nothing is not a test of power.

1. The words describe an impossible object. A rock too heavy for an omnipotent being is like a square circle or a married bachelor: the terms cancel each other, so no object answers to them. "Can God make one?" is grammatically a question and logically a blank. It is not that God lacks the strength; there is no rock to be strong against.

2. Omnipotence never meant "can do nonsense". Classical theology defines it as the power to do anything a perfect being can do, which excludes contradictions, not because God is limited but because contradictions are not things. Aquinas put it this way in the Summa: God cannot do what is self-contradictory, and this belongs to his perfection rather than diminishing it.

3. Nobody thinks weakness explains other impossibilities. God cannot make the past not to have happened. He cannot make two plus two equal five, or a triangle with four sides. No one concludes from this that he is weak, because none of these are tasks. Once that is granted for arithmetic, the rock follows.

4. Scripture's "impossibilities" are moral. "God is not man, that he should lie" (Numbers 23:19); he is the one "who never lies" (Titus 1:2); "he cannot deny himself" (2 Timothy 2:13). These are not failures. A God who could break his word would be a different and worse being. His inability to lie is what makes his promises worth trusting.

5. The verse about all things has a context. Jesus says "with God all things are possible" (Matthew 19:26), and the disciples had just asked who can be saved. He is talking about God doing what humans cannot, not about God performing contradictions. Reading a general statement as a blank check ignores the sentence it sits in, which is a rule that applies to both sides of this debate.

6. The picture behind the question is the problem. The paradox imagines God as a very strong hand among hands, then asks the hand to outdo itself. That is a creature with a bigger muscles budget, not the ground of all being. Once you drop the picture, there is no contest left to stage, because there is no second thing for God to compete with.

7. The dilemma equivocates on "can". In one sense God can lift any rock that exists. In the other, the rock in the question does not exist and cannot, so there is nothing for the second horn to name. The argument needs one word to mean two things at once. That's not a paradox; it's a pun.

8. Even the logic is borrowed. The question only works if logic is a real standard that binds even God. That is a theistic assumption: on the biblical view, God's own nature is the ground of order, which is why the universe is rational enough to investigate. An objection that depends on objective logical laws is standing on ground theism supplies.

9. What this does and doesn't settle. Answering the rock does not prove God exists; it only shows this particular objection fails. A paradox can be dissolved and the underlying question — is there a God at all? — still be open. That question deserves the cosmological, moral, and historical arguments, not a riddle.

The rock question is a linguistic puzzle that trades on a childish picture of power. Define omnipotence as the ability to do all that is consistent with being God, and the dilemma evaporates without costing anything. It was never an argument against God; it was an argument against a bad definition.

Sources: Thomas Aquinas, Summa Theologiae; Norman Geisler, Baker Encyclopedia of Christian Apologetics; William Lane Craig.

Related challenges:
• My Grandma was a sincerely nice person who happened to NOT be a Christian. Let me get this right...your "all-loving" God is going to punish her in hell for eternity because she didn't "accept" Jesus?
• Is it fair that a North Korean woman who never heard 'boo' about Jesus, let alone the Gospel, is going to burn in hell for eternity because she didn't choose the right set of parents, geographically?
• If God is all-good, why does God allow natural disasters, i.e. earthquakes, hurricanes, and tsunamis?