Very simple.<quoted text>
You just have to love the circularity here. You assume there is a God that says this. And then you disbelieve the people who are right in front of you who say differently about themselves. Why should we believe you when you say there is a God?
I point to God as a basis for my absolute standard of morality.
And as He is eternal and all powerful, that makes perfect sense.
You however, claim you do not believe in absolute moral standards, so there is nothing to stop you from lying.