2 Samuel 22:3 KJV says, “The God of my rock: in Him will I trust: he is my shield, and the horn of my salvation, my high tower, and my refuge, my savior; thou savest me from violence.”
It's in Him that we should put our trust to protect and keep us. He is our shield from danger and the source of our salvation. He is also our mighty high tower, our refuge and our savior. David calls God “the horn of my salvation,” referring to the strength and defensive protection animals have in their horns. God had helped David overcome his enemies and rescued him from his foes.
Help is in the Word
Today, the Word of God can be our source to deliver us from all dangers of life as we experience (driving, flying, sickness/diseases). Yes, we need protection from affliction that the enemy uses to attack our body. This is why: “Jesus Christ bore my (our) sins, sickness and diseases on His own body upon the tree (cross) and with the stripes that he bore upon His body for me (us), we were healed” (1 Peter 2:24 KJV).
God's Word says we are the redeemed of the Lord and whatever we say according to His Word “is so” (Psalms 107:2 KJV). So from this point on, whatever you say, according to God's Word concerning prosperity, protection, healing, peace, joy, “is so” and will come to pass.
Faith is a key component of the Word, however most of us may not be aware that they are supposed to mix faith with the Word to get results. However, when faith (complete trust) is applied to the Word of the living God, whatever mountain you speak to according to what the Word says, must obey the Word you spoke and be removed and cast into the sea according to (Mark 11:23 KJV) and cannot return a second time (Nahum 1:9 KJV).
It must be clear that the Word that you speak is not your word but God's Word. According to Isaiah 55:11 KJV, “So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I (God) please, and it shall prosper in the thing whereto I (God) sent it.”
What the authority means
As a believer, you should know that it is important to have the Spirit of God upon you. Jesus operated in a victorious manner every time he took the initiative to do something. He knew the Spirit was upon Him, which gave Him the ability to speak with authority/power over the situation. He knew He needed the Spirit just like we also need the Spirit to accomplish our task. “The Spirit of the Lord is upon me.” (Matthew 28:18-20 KJV)
To be able to do the works of the Lord in an excellent manner, Jesus Christ had given us the keys to the kingdom, which is the power and authority of His Word (Matthew 16:19 KJV). So with them, we have the ability to bind (negative stuff) in the earth and (loose) the enemies' stronghold against us. We need the spiritual keys because we don't fight against flesh and blood, but against principalities of the dark world (Ephesians 6:12).