God is behind all natural laws, he is the creator of mathematics, physics, science etc.
In the end, God is also the source of ethics and morality, which are unchanging and absolute.
People can create only temporary moral which cannot stand the test of time.
Religion is merely an intermediary between God and men.
And as someone has well noted, what is most fundamental is that God is love and our Heavenly Parent.
God's love was his motivation for creation and the absolute morality he gave us as a guide to life.
Unchanging?
When was the last time you stoned to death a waitress who served you coffee after your Sunday mass?
Or killed gays when you saw them in the street?
You have been doing that^^^ stuff? Shame on you.
If we only knew what that unchanging morality is. LOL.
3000+ examples and counting.
Morality is created by culture and is temporal. What is moral in one culture is obscene in another and vice versa.
What was once considered moral in Christianity/Judaism/Islam is no longer moral today. Slavery, stoning people to death, etc.
All we do is stick them in prison, often for not hurting anybody, and often for life on top of it.
Morality is built into the human mind and brain by God. Sin has corrupted it somewhat, but morality is similar wherever there are people. What is different is the ways mankind carries out morality in the various societies.
God is a man-made construct to help you cope with the challenges in life.
A self-deluding psychological trick to help you survive in the complex world.
Your idea that God is a man-made construct is simply you making yourself into a god... a man-made construct.