It's a very old question:
"Can God create a rock that is too massive for Him to move?"
This question is designed to demonstrate that God's omnipotence is incoherent. It is said, if it's true that God can do anything, then, surely, this is a thing He can do. However, if He can, in fact, create a rock too massive for Him to move, then there is a thing He can't do.
Which is... Move the rock...
Either way, there is something that He can't do. Therefore, omnipotence is a self-defeating concept. And if omnipotence is impossible, then so is anything said to have that attribute.
Is that all it takes to disprove God? One question?
Why is it that Christians think that God is omnipotent? What even is that?
The word omnipotence is derived from two Latin words, omni, "all," and potens, "powerful," and means "all-powerful." (1) We get this "all-powerful" description when God is called 'El-Shaddai; and the Bible speaks of God's unstoppable power in no uncertain terms, Job 9:12; Ps. 115:3; Jer. 32:17; Matt. 19:26; Luke 1:37; Rom. 1:20; Eph. 1:19. (2)
But how does one exactly define omnipotent?
I think omnipotence ought to be understood as, "God has the power and authority to do whatever He wills."(3)
"Whatever He wills," is the important part of that definition. To the Christian who has been around for a while and has read their Bible, it's no surprise at all that there are things that God can't do. The Bible has no trouble saying that God can neither lie, sin, change, nor deny Himself, Num. 23:19; I Sam. 15:29; II Tim. 2:13; Heb. 6:18; Jas. 1:13,17.(2)
So, what's the problem with the Rock question? Why is this one different?
The difference is that there is nothing about the question that is contrary to God's nature. It's not like asking God to sin and violate another aspect of who He is. It deals with the concept of being almighty itself. But there is one small, tiny, itty-bitty problem with the Rock question.
The question makes no sense. To better understand why this is, I'll reframe the question:
"Is God's omnipotence stronger than God's omnipotence?"
The only rational answer is, "... What?"
God's omnipotence just is His omnipotence. It can't be stronger than or weaker than itself.
Now it's been posed to me that since we are capable of creating rocks too massive for us to lift, this proves that the question is not incoherent and that we can do something that God can't. But this stems from a failure to appreciate how God relates to the physical world. You and I are physical creatures, inside this physical realm (world). We can interact with the preexisting materials within this physical world to construct an object too massive for us to move. But that is a big difference from God. God is not a physical creature inside this physical world. He is its creator and sustainer (Col 1:16,17; Heb 2:10).
God relates to our physical world in a similar way to how J.R.R. Tolkien relates to the world that he describes in the Lord of the Rings. Just as J.R.R. Tolkien is the author of the Lord of the Rings, God is the author of our physical world.
Now, I'd like you to close your eyes... Nevermind. I forgot that you're reading...
I'd like you to imagine a rock. This is a big, massive rock. It's resting in an open plain and can't be moved as you push against it. It's simply too heavy for you.
Now, that same rock is no longer in the plain next to you but is careening through outer space and is on a collision course with Earth. It lazily spins as it enters the Earth's atmosphere. Flames flare on the face of the rock as it hurtles towards the plain you're standing in. Smoke billowing behind it like the black and tattered shawl of certain death. And, OH, the noise! It sounds like the rumbling siren of doom screaming, "Woe to the living!" You feel the air whipping around you as if it's trying to make a mad dash for safety. And then... *pop*...
As if it had never been there to begin with.
The "almighty" person who brought that rock into and out of being was you. The person who changed that "immovable" rock from a state of rest to a state of cataclysmic motion was you. While you might not be able to imagine moving that rock as a creature within your imagination (very similar to how Jesus was God incarnate and surely built things that He couldn't move), nevertheless, any change in state to that rock was brought about by you. And you'll find that there is no rock, no matter how massive it is, that you can't alter from a state of rest to one of motion; or vice versa. The rock could be as big as Jupiter and it takes no effort to move it. There is never a rock that you can conjure that you can't also move.
That is how it is with God. And that is why the question is incoherent.
(1) Grudem, Wayne. Systematic Theology (p. 216). Vondervan
(2) Berkhof, Louis. Systematic Theology (p. 57). Eerdmans Publishing Co - A. Kindle Edition.
(3) Thiessen, Henry. Lectures in Systematic Theology (p. 126). Eerdmans Publishing Co.