Faith is a force in your spirit

1 Tim 1:5

“Now the end of the commandment is charity out of a pure heart, and of a good conscience, and of faith unfeigned.” KJV

“The whole point of what we're urging is simply love — love uncontaminated by self-interest and counterfeit faith, a life open to God.” The Message

“The purpose of this command is for people to have love, a love that comes from a pure heart and a good conscience and a true faith.” New Contemporary Version

We are still examining counterfeit faith. Jesus said whosoever shall say to this mountain be thou removed and be thou

cast into the sea and shall not doubt in his heart but shall believe that those things which he saith shall come to pass , he shall have whatsoever he saith. 

The place where doubt can begin to have negative effect on you is in your heart, not in your head or mind. Therefore, real genuine faith too resides in your heart. 

 If faith is in any other place it is counterfeit faith and will not produce result. I heard a man of God say that what some people call faith is nothing but a strong mental assent, that is, a strong persuasion of the mind. 

Though that is a good place to start but it is not real faith until it becomes a force in your spirit. Meditation will transfer your strong persuasion from the mind to the heart.