Is good "good" because God is good?

[KravMagaSelfDefense]

there is nothing good or bad persay.goodness and badness are relative and keep changing there sides as per needs of individuals and situations. killing is bad, but if a soldier while defending kills enemy soldier is doing good.i think any act which helps in propagation and harmonious relationship in human race is termed good and has always been fed to us as good. as the fear of unknown has always been successful in keeping the humans away from fighting each other,relating acts which are helpful for human race to god has made god appering good to us and good as god to us.

That is like saying that 2 + 2 is not always four, it makes no sense because moral law is absolute. It is not our mere opinion that killing breaks some mysterious standard, we KNOW it breaks a standard and by that we know there IS a standard. If I were to espouse the position you represent in your quote, then the implication is that things stop having moral value after I die. Because morality is just in my mind. But this is nonsense; we all know that actions and decisions had moral value before we were born and will have it after we die. Think about it, do you just "think" killing is wrong? Or is it more that you KNOW killing is wrong? If it's the second option, then who told you killing was wrong? And how is it wrong in a universe dictated by no law but the laws of physics