God did not create reason, it is an integral part of His nature. It cannot serve to cover the truth, for it will only expose whatever it covers.
In the same way, morality is not an invention of God, but an integral part of His nature. His goodness cannot hide what is bad, but will expose whatever it touches.
So reason and morality are inextricably linked. You cannot deny the absolute nature of morality, without deny the reasoning behind your own declaration.
It is like saying, 'there is no metaphysical realm'.
That is a metaphysical statement...
Or that, 'there is no truth!'
Then that statement is false...
Or that, 'there is no God.'
Then you must be omniscient and therefore God....
Morality is absolute, and I am right about it!
That is why I fled to the cross. Because the truth is, I would be 'rightly' condemned by a 'real' and absolute standard!
If you don't believe that, then you are consistent in saying morality is not absolute. I see no moral requirement to be consistent within your framework, yet you are careful to remain so...
Let us reason together!
Rob