There are two sides to things in life. The good and the bad. The good comes from God, the bad from the devil. You should only ever have one side included in your life. This dominates over you, teaching you what is the truth and what isn't the truth. It's in control of your life and your choice you have to make is whether you will let it. You have to make a good decision.
Many people sadly have let their lives be controlled by the bad side, the wrong side. Fear and doubt start to settle themselves right at home and we sit back and refuse to take it by the hand and tell it to GO! To take it by the hand and tell it to leave is crucial. Crucial in your walk of faith with God especially. We are not to have evil in anything in our life. It can alter our views on things and that's a big thing in life. We would make bad choices if that were the case. The best we can do is get rid of as much as physically and spiritually possible.
The biggest thing we need to have in order to conquer our fear is the word of God, God himself, and your faith. Your never-ending FAITH, never-failing GOD, and the never-deceiving WORD-OF-GOD. Take it all and encounter your fears strong. That's a strong thing.