This is obviously not a new idea, but is one that I found perplexing when I was a theist.
Mere morals have to make decisions based on imperfect information,imperfect reasoning, and imperfect intentions. This mostly results in multiple options. Humans are likely to change or adapt decisions as a result of new knowledge, unforeseen circumstances and other factors that result from imperfections.
This line of reasoning obviously doesn't apply to God. If God had to exercise a right to change his/her mind this would imply that there would be a need to do so. This would only applicable if the choice in the first place was not perfect.
The assumption that God is perfect, all knowing and all powerful, implies that all that God does is based on perfect knowledge, perfect foresight of the future, perfect reasoning, and perfect intentions and can only act in the perfect way, and this therefore cannot be changed.
