Because he jumped. Suppose he wouldn't jump. I might coax, and he may nod yes. Faith is active, not passive. Faith takes a stand.
Faith makes a move.
Faith speaks up. There are a lot of Christians who claim to have great faith in God but are spiritually lethargic and don't do anything. If it isn't expressed, it isn't faith. In order to believe God and His Word, we must do what He says. If you don't do what He says, you don't really believe Him.