Psalm 91says that God will deliver us from the snare of the devil.  That
means when the devil lays a trap for us, God will warn us to turn aside so that we will not be harmed.  Therefore, our ears must be tuned to what God is saying, and tune out other voices.  God also promises to deliver us from pestilence.  What is that?  Deadly and devastating diseases.  These are sicknesses that come unexpectedly and there seems to be no medical cure for them.  We must have faith in God to not only protect us from the devil but also to protect us from deadly diseases.  We build up our faith by knowing what the Bible has to say about the power of God.  We must live by faith and not by sight.