Abraham might seem to be a madman by today's standards, when he almost sacrificed his son at God's command.
Yet, when Yahweh told Abraham to sacrifice his son, it wasn't a strange request. Various gods in those days demanded human sacrifice, even child and infant sacrifice. (They still do, but they're in hiding now - or they acquire it through surreptitious means.)
Abraham obeyed the command, but when he took the knife to strike the killing blow, a messenger ("angel") of Yahweh told him to stop. (Just like action movies, where they always defuse the time-bomb with seconds to spare.)
And what was the message this messenger was sending?
"I'm not that kind of God." - Yahweh