Is something good because God says it is good; or does God say something is good because it is good? The question as old as Plato, and as current as this morning.
If we argue that something is good because God says its good, then we have to accept as good genocide (Deuteronomy 7:1-2; 20:16-18), slavery (Leviticus 25: 44-46), the stoning to death of non-virgin brides (Leviticus 20:10 & 13), and a host of other immoral acts made moral by God. And if we say that these good deeds are no longer good, but bad; no longer moral, but immoral, we will have to show where in the Bible (Jewish or Christian) God changes His mind. If we can’t, then you will have to admit that we are changing God’s mind, which may not be moral at all.
If on the other hand, we argue that God affirms what is already in and of itself good, then we would have to admit that God, at least when it comes to morality is irrelevant.
Morality is not a stationary target. Slavery was moral once, but no longer. Sexism was moral once but no longer. Anti-Semitism was moral once but—outside of some liberal colleges, universities, and not so liberal White Supremacist groups and madrasas, is no longer. And God had nothing to do with these changes. In fact there are some among the godly who insist that God still demands sexism despite the shift in secular thinking on the matter.
The interesting thing isn’t what God thinks but what people do. Atheists and believers act exactly the same when it comes to morality: each decides what is good and then looks for a rationale to back up their choice. Atheists may look to science, theists to God, but neither is willing to admit that they just made it up.
So you can be good without God and you can be good with God because in the end people can be good and bad and God really has nothing to do with it.