Many if not most believers would characterize God as being omnipotent and omniscient. Yet at the same time many see God as unable to do certain things, which of course is a contradiction or at least a paradox. The skeptics have often used the concept of omnipotence and omniscience as the means to challenge the Bible and by extension the whole idea of a Supreme Being. Everyone is familiar with the question: Can God create a rock so big that He cannot move it? Or why does God allow suffering if He is all powerful and could therefore prevent it?
The orthodox quite often describe God as being unable to look upon sin or to forgive sin unless the sinner actively, consciously, and correctly seeks such forgiveness and subsequently maintains a proper status before God by right living. The overarching attribute of God, in this scenario, is His need for justice. Justice trumps every characteristic of God, His love, His mercy, and even His stated will.
The Bible does indeed speak of what God cannot do. He cannot lie. His word of promise is immutable. God cannot fail (Love never fails). He must achieve His purpose. These two “cannots” are the true “trump cards” of the Bible. God has promised blessings on all and that promise must be fulfilled. It cannot be otherwise because God would then become the liar and failure which He cannot be.