The opposite to a spirit of faith is the spirit of fear. It is impossible for both to exist together. One will be prevalent over the other, and ultimately win. If you are fearful, your mind is not well-balanced. If you doubt God, then you am double-minded. But if you exercise the spirit of faith which God has given (2 Timothy 1:7), you can discover peace when faced with circumstances over which you have no control.
You must come to God “with no wavering (no hesitating, no doubting). For the one who wavers (hesitates, doubts) is like the billowing surge out at sea that is blown hither and thither and tossed by the wind. For truly, let not such a person imagine that he will receive anything [he asks for] from the Lord. [For being as he is] a man of two minds (hesitating, dubious, irresolute), [he is] unstable and unreliable and uncertain about everything [he thinks, feels, decides]” (James 1:6-8, Amplified).
The spirit of fear wishes to destroy your faith by making you “unstable, unreliable, and uncertain” about everything. It wreaks havoc on your thoughts, and weakens your faith in the promises of God. As a Christian you know you should believe that God's promises of love are true, and you do to a certain extent. However, your fears and doubts reveal that deeply-rooted within you are beliefs that are totally opposite to the promises of God. And the Word says that a double minded person should not expect to receive anything from Him.
This is God's truth, and promise. Study God's Word. As you start to face and realize the beliefs within you that are contrary to God's Word, you can apply His Word to your life. Faith begins to grow, and has greater strength to defeat the spirit of fear within you that you have been unable to control. You don't have to be double minded, unstable and uncertain. You can have God's peace and learn how to overcome your fears and your doubts. God's Word has the power to pull down these strongholds in your life. Learn it. Apply it. Pray and ask for God's help. He is always available. Don't ever give up. You can be free of the spirit of fear.