Behold, I give unto you power to tread on serpents and scorpions, and over all the power of the enemy: and nothing shall by any means hurt you.
Note 3 at Lu 10:19: Although these are examples of God's protection from harm by the physical creation (Ge 9:2, Jdg 14:5-6, and Ac 28:3-5), this scripture is speaking of mastery over the spiritual realm of the enemy (i.e., Satan). This scripture does not say that Satan cannot inflict any harm. The Scriptures abound with examples and warnings of the enemy's damage on the godly and the ungodly alike (2Co 2:11, 2Ti 2:26, and 1Pe 5:8-9). However, he cannot harm us when we are walking in faith in Christ's redemptive work.