My basis for saying so is based on the fact that Scripture teaches that God is the same yesterday, today, and tomorrow. If something is wrong today, it was wrong yesterday and it will be wrong tomorrow. He’s not going to change His mind.
As I said, the Ten Commandments are implied as enforceable prior to Sinai, because He was holding man to account on those same commandments prior to Sinai. Whether it be Cain or mankind. You can’t say something is wrong or evil without there having been a measuring stick as to what it means to be good. Do you deny that Cain knew he had done wrong? God never said up until this point that it was wrong to kill, but Cain knew he had done wrong and he lied about it. If you have an awareness of what it means to do wrong, it can only mean that you were aware of what it meant to do right.
Do you deny this?
What I deny is the Ellen G. White/Seventh Day Adventist lie that you repeated;
“The Ten Commandments existed at the time of man’s creation.”
What I detest is the way that SDA’s try to weasel around what they say by inferences, as you are doing. Either the “10 commandments” existed at the time of creation, and you can prove it by Scripture alone, or it is extra Biblical, and it is to be denied as the lie that it is. Scripture tells us of one commandment given in the garden, and it wasn’t written on stone.
Do you believe that Ellen White was a prophet of God?