In today's Gospel reading from Matthew 10, Jesus says, "Fear no one...And do not be afraid of those who kill the body but cannot kill the soul; rather, be afraid of the one who can destroy both soul and body in Gehenna."
I think there are a number of different ways we can take this. First, this is a reference to Satan. Satan tempts us and if we follow him, we lose body and soul. That should be the most frightening proposition of all. We must also fear God, and his just punishment. We must be deathly afraid of offending God, for fear of losing our soul.
I submit there is only one human you should fear. Yourself. You see, God doesn't send us to hell. And Satan, in the end, has no say in our eternal destiny. We get to choose our eternal destiny. And we must make this choice every moment of every day. So always be mindful of yourself, and afraid of giving in to the darkness that lurks within.
Father, keep us far from Satan, and give us a healthy fear of your just punishment. May we choose heaven, and you, every moment. Amen.