First Samuel 15 verse 3 states: "Now go and attack Amalek, and utterly destroy all that they have, and do not spare them. But kill both man and woman, infant and nursing child, ox and sheep, camel and donkey."
God is speaking through the prophet Samuel to King Saul, telling him to utterly destroy the Amalekites because they wickedly pursued the weakest of the Israelites as they were coming up from Egypt. But He offers no further explanation. Though we'd really like one.
Why kill the children, too? Seems a bit extreme...
But God offers no explanation. Even though it means that His actions and intentions will be misunderstood and misrepresented. He says nothing more than needs to be said. The expectation is that King Saul will obey the voice of God. King Saul, however, fears the people more than he fears God, and so he does not fully obey God--but that's another story.
The long and short of it is that God doesn't owe us an explanation for His actions.
You will notice in the Scriptures He rarely gives one. Especially where we'd most like one. I think He does that intentionally, because we can often forget who is God--He is; not us. Explanations belong to Him, and we as creatures are really on a need-to-know basis. There are things that will always be hidden to our knowledge, and we need to accept that and believe in faith that God is good, He is much wiser than we are, and we are bound to follow and obey Him; whether He gives us any explanation or not is His business.
However, a truly beautiful reality is that God does care about us! He does not give us explanations often because it's our human pride that wants one. But He often gives us explanations as a loving Father to a beloved child. He is a merciful God. And He promises not to break the one who is already bruised. If you are humbled by affliction and trial and pain, turn to God and not away from Him, and He will comfort you. But He will not give explanations to satisfy the proud and intellectually curious. He opposes the proud, but gives grace to the humble.