Isn't the Old Testament God Immoral?

How can the God of Israel be the good, just Creator reason reaches, given the violence and harsh laws of the Old Testament?

The objection, at its strongest:

1. Reason reached a God who is the very ground of goodness and justice.
2. But the God of the Old Testament commands conquest, sanctions slavery, and issues harsh penalties — behavior that looks, by any ordinary moral standard, cruel.
3. So the God of Israel cannot be the good God reason discloses. Either the texts are wrong about Him, or He is not worth worshipping.

In response:

What He does according to His will He does justly... But whereas law comes to us from some higher power, God is a law unto Himself.

— Summa Theologiae I, Q. 21, A. 1, ad 2

• The objection borrows the standard it uses to accuse. To call these acts evil is to appeal to a real, binding moral law that stands over God and everyone. But this stage argued that the Creator is the ground of that moral law. You cannot coherently use morality to indict the very source that makes morality more than preference. The force of the objection quietly depends on the theism it attacks.
• Read the trajectory, not just the snapshot. The Law of Israel is not presented as a timeless ideal but as a stage in a long pedagogy — God meeting a people where they were, then drawing them upward. Many provisions that shock modern readers are restraints on practices then universal (limiting vengeance, regulating and humanizing servitude far beyond the surrounding cultures), not endorsements of them. The Scriptures themselves press toward the prophets' fierce insistence on mercy and justice, and beyond.
• Genre and hyperbole matter. Ancient Near Eastern conquest accounts use stock, exaggerated language ("utterly destroyed," "left none alive") that the same texts then contradict by describing survivors — a rhetorical convention, not a body count. Reading such passages as flat modern reportage misreads what they are.
• The hard cases remain hard — and the tradition knows it. No serious believer pretends every passage is easy; the Church has wrestled with these texts for two millennia, often reading them on multiple levels rather than flatly and literally. But "this is difficult" is a long way from "this refutes a good God." A few genuinely puzzling episodes do not overturn a portrait that is, on the whole, the most morally demanding of the ancient world — a God who commands care for the widow, the orphan, the stranger, and the poor, and who judges His own chosen people by that standard. The deeper question of why a good God permits suffering at all is taken up separately in The Problem of Evil.

So the Old Testament does not show an immoral God undercutting reason's good Creator. It shows a God engaging a real, fallen people inside real history — which is exactly the messy, in-time involvement a personal God who acts by covenant would produce, rather than the tidy abstraction wishful thinking would invent.