Faith is a substance. It is not a figment of man's imagination, neither is it a psychological state of mind. From the reference above, it is substantial; it is a tangible "takeable", "handleable" force. Faith – Biblical faith, Christian faith – is something of substance, something solid and tangible. It’s the objective evidence in the here and now, of a bigger picture that goes beyond the here and now.
The Bible makes us to understand that the “just shall live by his faith.” This means, it takes faith to be alive spiritually. It is therefore important to build our faith. The failure of one’s faith is the failure of such a person’s life. Even Jesus Christ had to pray that Peter’s faith would not fail. Therefore, I pray for you that your faith will not fail in Jesus’ name. Peter walked on water because his faith was at work but the moment his faith failed he started to sink. He then cried out to Jesus for help. Jesus helped him up and Peter walked back with Jesus to the boat.
Above all, taking the shield of faith, wherewith ye shall be able to quench all the fiery darts of the wicked - Ephesians 6:16
"Taking the shield of faith." If faith is not a substance, you cannot take it. The fact that I said faith is a tangible force does not make it physical. It is definitely as real as the air we breathe, and equally invisible to the human eye. It is therefore a spiritual entity, a living force. It is the trigger that provokes supernatural interventions. It is beyond the mental sphere. True faith begins with God. And leads to a response in us.