God and Nihilism
You could say that murder is impractical or that murder is something 'I do not like' but there can be no such thing as "wrong" or "right" strictly defined.
Try to explain why murder inherently wrong if there is no God? We do not cry when frogs are chopped up in our lawnmowers or mosquitoes splash on our windshields as we drive.
Why is human life particularly important? Other than practical reasons (I do not want to go to jail) or emotional reasons (murder makes me feel yucky) why would murder be wrong at all?
Which brings us back to that truth..... without some sort of God, the entire human experience from the earliest days of man to whenever this world ends, even if that period is millions of years, will just be a brief spark in relation to the sea of dead time that preceded it and will follow it. There will be no one around to remember any of it. Whether we are funny or boring, kind or mean, loving or cruel, just or unjust, in the end won't matter.
Unless... there is some sort of God. As a Christian, I say murder is wrong because human life is important (more important than the frog that died and more important than the mosquito). Human life is important even in cases where it does not affect me directly (some distant disaster). Human life is important regardless of emotion, feeling, or practicality.
Why is human life important? What is it about a living human being that makes murder not just impractical or emotionally distasteful but "wrong"?
The Christian answer is that humans are made in God's image. We are a reflection of the divine. And destruction of this image of God is an offense to what belongs to God. God alone can take and give life. We are thieves and murderers when we do it.
Without God, nihilism is unavoidable.