“For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.”  
Romans 8:15

The main verse further emphasizes the ministry of the Spirit in our lives, where he is, there is liberty. He says we have not received the spirit of bondage again to fear! This means there is a spirit of bondage that others are being influenced by; and he tells us the expressions of such people- fear!
They are easily shaken by any sudden happening. While the fear they exude is based on their mental apprehension of the situation, the word of God reveals to us that there is a spirit of bondage influencing them; such a spirit that has held them bound to the thoughts of fear so much so, they can’t think of anything else.
For those of us that are Christians, he says we have received the Spirit of sonship; we are children of the living God:
“And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.”  Romans 8:17
And he tells us the consequence of our sonship; we are heirs of God! Hallelujah, this means emphatically there is nothing to fear. We are heirs of his authority, ability, resource and name, the one that all beings tremble at the thought of him is our father, our portion and our purpose!
“The LORD is my light and my salvation; whom shall I fear? the LORD is the strength of my life; of whom shall I be afraid?”  Psalm 27:1