So then what is good? The absence of evil? Is evil the absence of good? What a great circular argument.
Think about a good act: Someone gives a needy person a meal. Is there a better act? Someone gives a needy person a meal and a place to stay. Is there a neutral act? Someone walks by a needy person without realizing the needy person is there or in need. Is there a bad act? Someone takes the needy person's coat. Is there a worse act? Someone assaults the needy person leaving him in pain.
Now if we remove the bad and worse acts, does it leave good without definition? Of course not, there is the neutral act. If we take away the neutral act, is good without definition? Of course not, because then we would not recognize the difference between "good" and "better".
To find the definition of good and evil, you need look no further than the Good Book. God clearly defines what He considers good to be.
You say that some acts are neutral. I disagree. Even to evaluate an act as neutral you are first determining that it is better than the bad act.
Don’t you see that this leads to the reasoning that the first act is bad and the second is good? It is your human mind that is evaluating it.
But with God, good and evil are written out in black and white.
I think of good and evil like I think of white and black. White is all color. Black is the absence of color. You may determine that there is a gray, but again, the gray is a little better than the black, in that it is X number of steps closer to white.