God would not make a rock so big that He can’t lift it. God is omnipotent and He has all power over all things at all times and in all ways (Job 42:2). But omnipotence does not mean that He can do literally everything.
God is holy and He cannot sin (Psalms 78:41). God is truth and He cannot lie (Numbers 23:19). God cannot change His nature (Malachi 3:6). And God cannot deny the demands of His holy character (Psalm 71:22). God can’t change His moral or physical laws (Matthew 5:18).
And if we examine closely the plan of salvation we will see that despite His being all-powerful and hating evil, God allows evil to happen because He granted the freedom of choice to His intelligent beings. God is love (1 John 4:8). And only Love would give free will to His creatures and run the risk of having the suffering that sin has caused the Godhead.
The God of love desires only the voluntary love of those who have free will (Joshua 24:15). And when sin came, The Godhead came up with a plan that would allow the universe to understand the basic elements in the great controversy between good and evil, and thus make sure that sin will never arise again.
The Father sent His Son to redeem the human race from the guilt and power of sin by His earthly life, death, and resurrection, and then to become the Head of a new and sinless beings (John 3:16). In the battle against sin, God, being truly love, can use only truth and love, whereas Satan uses deception, lies, and hateful force.Thus, there are things that God, though all powerful, can never do.
In His service,