Reason is the ability that God has given us for understanding the truth. It is the only ability God has given us for doing so. It is impossible to use the ability correctly and not agree with God. It is impossible to use reason correctly and "make up your own definitions of good and bad." God and bad are completely understandable by our reason. It is God who says, "Come, let us reason together...," (Isaiah 1:18) It is men who do not understand that reason is God's chosen way for men to learn the truth, that denegrate it.
Hank
I see where you are coming from and understand it. I have not, up to this point, been able to put it in words. There is just something screwy with what is being taught out there, and it is difficult to pin point it. I know that God is out there. I know that the bible is his word. But the "Christian" community leaves me searching for answers still. (That is not intended to knock any Christian on this forum.)
As I said before, evil people employ well-honed reason very well (Lex Luther, Mao Tse-tung, Hitler). When you say it's impossible to use the ability correctly and not agree with God, you're assuming something else (that which is correct), outside of reason.