You might have heard an atheist, agnostic, or skeptic claim that the idea of God is incoherent—that it doesn’t even make sense.  One way in which he or she might try to demonstrate this assertion is by asking you if God can create a rock so big that He cannot lift it.  The hope of the argument is that at best, you’ll be left with either an impotent God (if He can’t create such a rock), or at worst, you’ll be left with no God at all (if the idea of God is untenable).  Does this argument work?  I don’t think so.  And it’s not just that I disagree with the conclusion.  There’s something much more obviously wrong with it at its foundation.

TWO THINGS GOD CAN’T DO
First, Christians have never affirmed that God can do anything (without qualification).  Rather, the assertion is that God can do anything which is (1) consistent with His nature, and (2) logically possible. 

ONE
For a thing to be consistent with His nature means that it cannot go against His perfect character.  So, the Bible tells us that God cannot lie (Heb 6:18) and He cannot be tempted (Js 1:13).  Then does this mean that God is limited?  After all, I can do both of these things and God can’t!  Not at all!  That fact that He cannot do something (like have a false belief) is not a limitation to Him but a perfection.  The fact that I can and do hold false beliefs makes me lesser, rather than great, than God.  It’s precisely because God is perfect that He can’t do such things.

TWO
God also cannot do something which is logically impossible.  This is why the original question about the rock doesn’t work.  Suppose I asked you if you’d like to walk out to my car with me to see a square-circle my glove box.  Would you be tempted to come with me?  I hope not.  Reason being, you don’t need to come check it out to know whether or not a square-circle is in my glove box.  You know a priori (before any experience) that a square-circle is an impossibility.  The two concepts (square and circle) are mutually exclusive.  Or let me give you an even more obvious example that relates well to the original rock question.  What happens when an irresistible force meets an immovable object?  Trying to figure it out?  You can’t!  You can have a universe with one of these (an irresistible force or an immovable object) but not both.  The existence of one necessarily precludes the possible existence of the other. 

WHAT’S WRONG WITH THE QUESTION?
So, back to the original question.  “Can God create a rock so big that He cannot lift it?�  No one should be faulted for not give a “yes� or “no� answer to the question.  The problem is with the question itself.  The question is a meaningless question.  You might as well ask what purple tastes like?  It’s a category mistake to even ask the question.  God’s nature is such that He is omnipotent (all-powerful), and therefore, it would be impossible for there to be a rival power. 

Similarly, we could think of other qualities of His as well.  Another aspect of God’s nature is that He is an eternal being.  He cannot cease to exist (Ps 102:25-27).  Therefore, a question about God ceasing to exist is also a meaningless question given our definition of God.

These sorts of questions are what often times are called a “straw man� argument.  It’s an attempt to set up a weak and easily defeatable picture of the Christian God, and then knock it down in hopes of undermining the Christian view of God.  We must be equipped with the necessary tools of critical thinking in order to not simply answer question and also question questions.