I don't follow exactly what you are asking, the question is a bit muddled in my opinion.
First, how do you define evil? The original hebrew does not really have the same connotations as the English, closer perhaps to 'disagreeable' or 'bad'.
Evil can be said to exists only as a shadow of good, being not something itself but merely the absence of the other. For no one does evil for evil's sake, but searching for a 'good'. For instance, a serial killer doesn't kill to kill, but for the feeling it brings him or a murderer for some other aim, which is a good to that person.
Some argue it doesn't exist, that what appears evil to us would disappear in the big picture, that it had some worth, although these tend to be pantheists and I disagree with this contention.
Regardless, we cannot discuss the presumed character of God without agreeing on terms.
Second, is the problem of the radical nature of God. Temporal creatures such as you and I cannot properly grasp a atemporal being. For God would see every moment of our lives in the same eternal instant, thus see what acts we do as we do them, but seeing all such acts for our entire lives, thus maintaining free will. We have difficulty conceptualising this aspect, but then there are much greater mysteries. We can only understand God by applying human terms we understand like just or powerful or whatever, which really does not do the concept of God justice. Our terminology is woefully inadequate as we cannot really grasp His nature.
To borrow from CS Lewis, if we had a race that lived in a 2 dimensional world and they approach a cube, they would see a line. If they walk around it a square. They would not be able to conceptualise the cube even if someone tried to explain it to them as their worldview would have difficulty seeing a third dimension. The same inadequacy of understanding applies to God.
What we do know is what we can grasp and then try and backtrack to an understanding of what is essentially unknown and will of course be flawed, regarding God. In the analogy above, the square.
Now, most nations have more or less the same morality - don't steal, don't murder etc. - with notable exceptions like Sparta for stealing and such. The vast majority of moral codes agree on most points. Therefore, we can surmise, but not prove, a baseline human morality which must be either instinctual or cultural or of divine origin. The problem with instinctual origin is that it frequently disagrees with our instincts as when for instance someone is in a burning building - instinctively we would stay away, but morally we know we ought to help. In that word ought, we find morality as not being instinctual. If it was cultural, we would expect more differences than we see, although significant aspects of morality are definitely cultural constructs. We can construe this is from evolutionary development of cultures, but this fails the litmus test for concepts like theft, for these exist even in societies lacking the idea of personal property.
Therefore, the probability for a 'divine morality' at least in part is high.
Therefore we have a side of our square, that God maintains a form of our morality (or more precisely, we maintain a form of God's).
Third, no society worships an evil god. Even those with ambigious gods like Seth or Kali, they aren't evil. For the god of death or famine also keeps those things at bay and often they are more gods of change than decay. It is a conceptual shift we must make because popular media has made us convinced that acolytes of evil gods exist cutting hearts from chests etc. when they really aren't supported historically.
Humanity in general either sees its gods as neutral or benevolent regarding humanity.
Fourth, depends on your acceptance of historic revelations. God is unknowable by definition, but if He reveals aspects to individuals and we accept that revelation as accurate, then you base your view on that. For Christianity we have the actual Incarnation of God Himself, so there would be your answer.
If you disregard point four and depending on your definition of evil, we can at least say that God is likely a moral being, benevolent or at least neutral to humanity, whose morality is similar to our own as it is likely a vague shadow of God's morality.
Note: I have written this from the aspect that you accept God/s exists. If that first has to be proven to you, then nothing I have said would apply to your conception and the reasoning would be radically altered.
