Abraham knew God called him. He knew God gave him victories in war. He knew God gave him his son. But Abraham’s neighbors knew something more. They knew gods were fickle and needed gifts, or else they’d take away more than they offered. A real god wouldn’t let Abraham strut around with a second perfect child. “So kill him,” they said. “Your god needs to know you’re willing.”
Isaac knew God called him. He knew God loved and cared for him. So he carried the wood for sacrifice and he trusted something good. Their real God wasn’t fickle after all.