How can an all powerful supreme being be either good or evil? In order to be Omnipotent, or all knowing, as well as Omnipresent and all powerful wouldn't a supreme being have to be so far removed from concepts of "Good" and "Evil"?  Those are just terms and ideas that Man created, therefore how can something that is literally the sum total of everything be one or the other?
If you're asking for an answer from a Christian perspective, which implies that you will accept, for the purposes of the answer, the presuppositions inherent in a "Christian answer" such as that God is who the Bible claims he is...

You're making a false assumption in the question.  Good or evil are not concepts that man made up and applied to God.  Good and evil are concepts defined by God, and understood by us, his creation.  As the Creator of the universe, it is He who defines what anything is.  He created things as he saw fit, and if He says something is this, or something is that, it is so.  

We, as His creations merely understand, through the senses and ability to reason that he created in us, or through his revealed word to us.

Therefore God defines what good and evil is.  Being God, it makes sense that "Good" is defined as according to His word,in line with His character, and as revealed to us by Him.

It is only from an atheistic mindset that one could claim that "good and evil are traits we made up and applied to God".  The ability to say that cannot exist without the presupposition that God is imaginary, and a creation of man.  From the Christan perspective, this is exactly the opposite of the truth.